Aristotle: a Chapter from the History of Science

Aristotle: a Chapter from the History of Science, including Analyses of Aristotle's Scientific Writings was written by George Henry Lewes and published in 1864.

Note that each general third person reference in this article is to Aristotle, unless otherwise indicated.

Preface

 * Most expositions of Aristotle's doctrines, when they have not been dictated by a spirit of virulent detraction, or unsympathetic indifference, have carefully suppressed all, or nearly all, the absurdities, and only retained what seemed plausible and consistent. But in this procedure their historical significance disappears. ...I have allowed the errors and the crudities to take their rightful place beside the plausibilities and truths; thus preserving, as far as may be, the historical colouring derived from the inherent weakness of early Science, and the individual weakness of Aristotle.


 * It eminently desirable that the growing practice of secondhand citation should be discouraged; since our native infirmity renders us all sufficiently liable to error, without our taking on ourselves the responsibility of other men's carelessness or their misrepresentations.

Ch.1 The Life of Aristotle

 * It is difficult to speak of Aristotle without exaggeration: he is felt to be so mighty, and is known to be so wrong.


 * The splendour of his fame perpetuates the memory of his failure, and to be just we must appreciate both.


 * His intellect was piercing and comprehensive; his attainments surpassed those of every known philosopher; his influence has only been exceeded by the great founders of Religions; nevertheless, if we now estimate the product of his labours in the discovery of positive truths, it appears insignificant, when not erroneous. None of the great germinal discoveries in science are due to him, or to his disciples.


 * All ancient writers, except, perhaps, Thucydides, are uncritical in their reception of facts. Even in our own critical age, as it is rashly called, we find it extremely difficult to ascertain the truth respecting celebrated persons; so powerful is the mythical tendency, and so fungus-like the rapidity with which lies are propagated.


 * The ancients had not risen to the conception of what constitutes evidence; they were as credulous as children; and accepted almost any marvel which was narrated gravely.


 * Often in antagonism... he is never in hostility to Plato. Indeed, in the Ethics, he complains of the necessity of attacking doctrines held by "dear friends," adding—"It is our duty to slay our own flesh and blood where the cause of Truth is at stake, especially as we are philosophers; loving both, it is our sacred duty to give the preference to Truth." It is a timidity unworthy of a noble mind to shrink from intellectual opposition as an offence against friendship, and to suppress convictions for fear of misconstruction.


 * His heart was kind, as was manifest in certain acts, and is expressed in this saying, "He who has many friends has no friends," which profoundly touches the very core of the subject, and may be paired off with this other saying of his, "A friend is one soul in two bodies." When asked how we should behave towards friends, he said, "As we should wish them to behave towards us."


 * Advancing age and development, no less than the decidedly scientific bias impressed upon his studies, necessarily caused him to take up an independent position with respect to Plato, who had little taste for physical science, and whose intellect naturally withdrew from those very subjects to which his young rival was, by nature and early bias, strongly determined.


 * Had it not been for Alexander's princely aid, Aristotle's enormous collections could not have been made. ...Add to this the statement of Pliny, that Alexander gave orders to his hunters, gamekeepers, fishermen, and bird-catchers to furnish the philosopher with all the material he might desire—an order which at once placed several thousand men at his service. ...But at the same time remember it is Pliny who makes the statement, and for untrustworthiness of statement he cannot easily be surpassed; so that even here an immense exaggeration may be suspected; and to sum up remember that although Aristotle must have had a large collection of materials before he could have written his work on animals, Humboldt declares that there is no trace in that work of any acquaintance with animals first known through Alexander's expedition.
 * Footnote: Pliny Hist. Nat., VIII. 16.


 * After an absence of twelve years, B.C. 355, Aristotle reappeared in Athens. He found the Academy already occupied by his friend Xenocrates; so that some other place had to be sought where he might open a school. This he found at the Lyceum...But we must not suppose, as many suppose, that this establishment was placed under the direction of Aristotle, or that he had any voice in its affairs. He simply received permission to teach in the morning and evening at the peripatos, a permission which was the more acceptable because the shady walks offered facilities to his accustomed habit of walking to and fro during the delivery of lectures. ...Aristotle was by no means singular in this practice of promenading while he taught.


 * As a foreigner, a philosopher, and a friend of Macedon, he was trebly odious to the political leaders; and a pretext for accusation was raised on a ground where such pretexts are always easily raised and are always dangerous—irreligion. He was accused of blasphemy, and of paying divine honours to mortals. And who were these mortals he had honoured? His friend and his wife. ...The blameless life and lofty soul of Socrates had been no defence against the charges of Melitus; and Aristotle quitted Athens, "not to give the Athenians a second opportunity of committing a sacrilege against philosophy." ...An idle sentence of death was passed; but nature had already written that sentence in terms that were not idle. He died in the sixty-third year of his age B.C. 322.


 * His will, which may be read in Diogenes Laertius tells of his thoughtful kindness. His daughter Pythias, his son Nicomachus, his adopted son Nicanor, and his concubine Herpyllis, are all duly provided for, and some of his slaves are emancipated, others rewarded.


 * He is admirable for the intense urgency of his mind in seeking scientific explanations of phenomena, at a period when such explanations were novelties; and for the dominant inductive tendency which led him on all subjects to collect the facts before reasoning on them.


 * Plato was the most artistic of philosophers, and, among men of great eminence, one of the worst of investigators; not, assuredly, from deficient power, but from his disastrous misconception of Method. In spite of a certain loitering diffuseness of style, and an oppressive circumstantiality in refuting trivial considerations, no one before Plato, no one since, has managed the extremely difficult art of dramatic debate on philosophic topics with such commanding success; and in consequence of this fascinating art, aided by the union of dialectical subtlety with mystical yearnings, a subtlety which seems to give a hope to mysticism, and a warrant to transcendentalism, no one has exercised a more pernicious influence on culture. The charm of the artist has immortalized the vices of the thinker.


 * With Aristotle... His Method although imperfect... was not utterly wrong, but wrong only in one important particular; in direction it was wholly right. It was a Method which required development, and was not like that of Plato, one upon which rational philosophy was impossible.


 * As an artist, Aristotle is simply without rank and as a writer... he is many degrees removed from excellence. ...In works like the Politics, Poetics, Ethics, and Rhetoric... ...he is intelligible, and sometimes epigrammatic, although without charm. But where more severely tasked... his composition is rambling scattered and confused. There is little illustration, and no side-lights of suggestion. The want of artistic composition renders this absence of illustration a serious defect. When a writer's composition is good there is less need of illustration... But there are few writers who understand this art; and Aristotle understood it not at all.


 * Whatever may be the excellencies of Aristotle's diction (and these few moderns can pretend to appreciate), the defects of his composition are not matters of opinion, but of demonstration.


 * The history of Aristotle is for many centuries the history of learning.


 * Hegel and Sir W. Hamilton have done their best to impress on fluctuating public opinion the conviction that not only was Aristotle a thinker of vast power, but of present worth: not only great in his own time, but anticipating the truths of all time.


 * Cuvier, Isidore St. Hilaire, De Blainville, and Johannes Müller, drawing after them crowds of obedient disciples, have spoken of his scientific works as if they were on a level with the science of our day, claiming for him some of the most curious discoveries of modern research.


 * Among his modern eulogists will be found biologists, politicians, and metaphysicians, but no astronomer, no physicist, no chemist. In other words, in those sciences which have advanced to the positive stage, and in which the rigour of proof reduces Authority to its just position, his opinions are altogether disregarded; whereas in those sciences in which, from their complexity and immaturity, the influence of Authority and the delusive promises of the Subjective Method still gain acceptance, his dicta are cited as those of a puissant investigator.

Ch.2 The Dawn of Science

 * Science... begins when the forces of Nature are appreciated in their relations to each other; and in its highest flights all personal relations are merged in a grand disinterestedness.


 * To measure the ground; to measure the seasons and the length of days; to cure a disease or dress a wound; to plough the soil and garner the harvest; to guide a fragile bark along a perilous coast by the aid of the Pleiades; or "sailing stars;" to know that fire burns, liquids evaporate, and metals fuse—these are among the early experiences of the race, but they are not Science. They are the preparatory materials—items of that Common Knowledge which the energy of man, as he advances to maturity developes into Science.


 * Science as we now understand the word is of later birth. If its germinal origin may be traced to the early period when Observation, Induction, and Deduction were first employed, its birth must be referred to that comparatively recent period when the mind,—rejecting the primitive tendency to seek in supernatural agencies for an explanation of all external phenomena,—endeavoured, by a systematic investigation of the phenomena themselves to discover their invariable order and connection.


 * The separation of Science from Knowledge was effected step by step as the Subjective Method was replaced by the Objective Method: i.e., when in each inquiry the phenomena of external nature ceased to be interpreted on premisses suggested by the analogies of human nature.


 * The history of human development shows that there are three modes by which we conceive phenomena... The first of these supposes that the order and succession observed in phenomena, is due to the influence of outlying agencies—powers which are super natural, above the objects, not belonging to them. ...The attitude of mind which is based on the first of these assumptions is that which is common to all primitive theories. It characterizes what Auguste Comte names the Theological Stage in human development. On this assumption, all phenomena not of the simplest and most familiar kind are referred to the agency of invisible powers, spirits, deities, or demons. ...As this idea of will originates in the analogies of human volitions influencing human actions, the same capriciousness and variability which characterize human actions are supposed to characterize external phenomena.


 * Before men could refer the changes they observed to the influence of properties inherent in the objects, a strong conviction must have arisen that the order of succession in phenomena was not variable, but fixed. Invariableness would inevitably lead to the conception of all changes being due to the relations between the various properties of objects—first, by discrediting the interference of an external will, which is essentially incalculable; next, by disclosing that there was really no need of anything but the recognized or recognizable properties of objects to account for all changes.


 * Causation is now assumed to lie within, and not without, the circle of phenomena. Science, withdrawing from all speculation where it can find no adequate evidence, and where its methods are inoperative, refrains from inquiry as to ultimate causes, and says nothing respecting the mystery of creation.


 * The scientific mind replaces these gods and angels by laws of nature, according to which the planets move by forces similar, and under conditions similar to those observed in all other moving bodies. ...it gets rid of the presumed variability in the agency, and leads to the careful study of the inevitable order; instead of encouraging attempts, by prayers, supplications, invocations, or the sacrifices of animal life, to persuade the inevitable order to alter its course.


 * The metaphysical explanation is an obstacle, because it withdraws attention from the close scrutiny of facts, and deludes the mind with unverified, unverifiable assumptions.


 * So long as diseases were conceived to be the products of supernatural agency, their cure was properly sought in invocations, sacrifices, prayers, and charms, rather than in the study of the organism, and an accurate acquaintance with the properties of objects.


 * The theological, metaphysical, and scientific explanations have three different criteria, or guarantees. The guarantee of the first is sacerdotal. ...The guarantee of the second is somewhat less absolute; it admits of question, because it is based on reason, not on faith; nevertheless, any conclusion which can be logically deduced from general doctrines accepted by metaphysicians is held by them to be demonstrated. To the theologian it is enough if he can adduce a text. To the metaphysician it is enough if he can deduce his proposition from "clear and distinct ideas." The guarantee of science is in the verification of experience, direct or indirect. It distrusts the validity of à priori conclusions, or of any explanations drawn solely from general ideas of Nature's order, unless those general ideas have themselves been rigorously demonstrated to be necessities of thought, or to represent the observed order. What must be or may be has to give place to what is.


 * The general doctrines of Science are never, like those of Theology and Metaphysics, conceived to be final. However firmly fixed at present, they may be shaken tomorrow by a new discovery.


 * In every case Science welcomes scrutiny and scepticism; its final guarantee is conformity with fact.


 * While both the metaphysicist and the physicist draw conclusions from their general doctrines, the one is contented with logical symmetry, the other demands the confrontation with fact.


 * The ancient astronomers believed in the uniformity of the celestial revolutions, and in the circularity of their orbit. ...performed in perfect freedom and in periods rigorously constant ...From this assumption of uniformity, the circularity of the orbit was a necessary conclusion. The logical chain was perfect. It so completely fettered the mind as almost to bar the way against the admission of the truth. Kepler had difficulty in accepting his own discovery... Thus nothing could be more plausible considered à priori, than the ancient theory; nevertheless, no sooner were adequate means of Verification applied to the theory than the whole fabric tumbled down like a house of cards.


 * The Subjective Method claims direct knowledge of the nature of things and the ultimate causes of all changes. The Objective Method by looking at things, assuming the position of simple spectator, renounces all hope of ever penetrating the mysteries of existence, of ever knowing the intimate essence of things, and only hopes to detect the invariable order of co-existence and succession. The one claims a knowledge of "noumena," the other a knowledge of the laws of phenomena.


 * The superior exactness and certainty of Mathematics are due to the fact that no hypothesis is allowed to stand for more than an hypothesis; no deduction takes its place as a datum until it has been demonstrated.


 * Whenever the data and the deductions have been rigorously verified, the truths of Physics and Chemistry are as certain as those of Mathematics.


 * "Men who desire to learn," said Aristotle, "must first learn to doubt; for science is only the solution of doubts:" an aphorism, novel in those days, in our own a truism.


 * It is their [the Greeks] immortal glory to have recognized the necessity of proof; and this recognition was itself consequent upon their ceasing to interpret phenomena as the direct results of supernatural agencies.


 * The mysteriousness was not denied; it was simply set aside, removed from the sphere of scientific thought. The Greek had a free, independent spirit, adventurous, rebellious, curious; and boldly doubting, sought a solution of his doubts in his own way. He refused submission to established doctrines. He would accept neither priest nor philosopher as his oracle. Without directly contradicting the priest, he boldly erected his own Academy beside the Temple.


 * It was a weakness in them that they had little sympathy with that sense of the Infinite which characterizes some other eminent nations. This is visible in their Art: an Art matchless in clearness and proportion, in the beauty of arrested lines, and the repose of symmetrical simplicity; but having none of those finer issues which escape into the sublimity of Christian Art. Greek Art is a lute not an organ.


 * Aristotle... seems utterly destitute of any sense of the Ineffable. There is no quality more noticeable in him than his unhesitating confidence in the adequacy of the human mind to comprehend the universe... He never seems to be visited by misgivings as to the compass of human faculty, because his unhesitating mind is destitute of awe. He has no abiding consciousness of the fact deeply impressed on other minds, that the circle of the Knowable is extremely limited; and that beyond it lies a vast mystery... impenetrable. Hence the existence of Evil is no perplexity to his soul; it is accepted as a simple fact. Instead of being troubled by it, saddened by it, he quietly explains it as the consequence of Nature not having correctly written her meaning. This mystery which has darkened so many sensitive meditative minds with anguish he considered to be only bad orthography.


 * Science acquires her dignity, and her supreme power, from her noble disinterestedness. ...Use is secondary and derivative; the primary object is elucidation of the Truth. All Truth is beneficent; but her seekers desire to behold the serene splendour of her face, and not themselves to reap the benefits which spring up on her track. This attitude was first assumed by the Greeks. Their philosophers were content to seek wisdom as the one great object, without directly subordinating their search to Religion or to Use.


 * The attempt to explain Nature, without reference to the gods, very generally drew on philosophers the accusation of impiety. Nor was this prejudice confined to the vulgar and unthinking; it was shared and avowed by Socrates. ...The same thought has, in all ages, roused the bitter hostility of theologians, against the scientific attitude, as one essentially irreligious.


 * Science can only destroy false explanations, which it is for our welfare to have destroyed. No single truth can be shaken by Science. If in her own path she detects certain truths, these must necessarily be harmonious with all other truths. We must learn to welcome all, and to prove all.


 * Other peoples amassed details of knowledge, manifested intellectual activity, invented useful arts; but it is in the Greek writers that we must seek the inauguration of the scientific epoch. It is in them that, for the first time, appears the systematic effort to ascertain the relations of things objectively, to detect the causes of all changes as inherent in the things themselves, and to reject all supernatural or outlying agencies.


 * The Greeks began, but only began, this revolution. They carried it but a little way. Their explanations were generally inaccurate... and the eclipse which for several centuries darkened the day that had thus brightly dawned, was owing chiefly to the energetic revival of that very theological spirit from which the illustrious Greeks had emancipated themselves.

Ch.3 Ancient Science

 * We have to consider how it was that the Greeks and Romans, in spite of the splendour of their genius, made such slight progress in the discovery of physical laws. In Art, Literature, and Philosophy they have legislated for the world. In Science they are without authority.


 * The failure [of a Greek or Roman science] is generally assigned to a complete disregard of Observation and Experiment, together with a "fondness for abstract reasoning." ...A survey... detects the existence of two causes: a psychological and an historical cause. The first lies in the nature of the Method pursued; the second lies in the condition of knowledge at the period. On the Method pursued by the ancients, no satisfactory issues could have been reached, even had it been backed by the stored-up wealth of modern research... [The second,] there was no stored up material to form the basis of extensive discovery. Science is a growth. The future must issue from seeds sown in the past. The bare and herbless granite must first be covered with mosses and lichens, if from their decay is to be formed the nidus of a higher life.


 * From the small beginnings and successive growths of knowledge there emerges a more comprehensive and more complex Science. The advance is not simply one of addition but of new development—a development rendered possible by the addition... The truth sought in one age as a goal becomes a starting-point to the age which follows; the discovery which was the passionate aim of one man, and conferred on him lasting glory, becomes to his successors a mere instrument of new research.


 * No one who reflects on the actual condition of any science, will fail to notice the complicated connection of all the sciences. The perfection of one demands illumination from all. ...This connection of the sciences points to a simultaneous growth, and a slow growth. Therefore in the early ages before a large mass of established truth had been accumulated, before instruments had been invented, and when discoveries which were to be the instruments of research were still unsuspected, it almost was impossible for any mind, however great, to give a scientific explanation of any class of phenomena; all that could be done was to suggest some happy hypothesis, or to work out some small point of special value.


 * The majority, especially of philosophers, were too impatient; and unable to rest without some explanation, trusted confidently to the Subjective Method, because the Objective Method could not then have been constantly applied so as to satisfy their intellectual cravings.


 * Before we can explain the failure of the ancients we must rightly appreciate the influence of two different and concurrent causes, methodological and historical. Those writers who... have treated this subject ex professo have entirely overlooked the historical cause... Nor does it seem to me that they have been successful in very distinctly marking the sources of failure even with respect to Method. They have felt the defects rather than assigned a philosophical explanation of them. An exception must be made in favour of Dr.Whewell, who has brought his views on the philosophy of science to elucidate this very question.


 * Experiment, by varying the circumstances which usually accompany the phenomena, endeavours to disengage the conditions which are coincident from the conditions which are causally related.


 * Observation gives us the fact with great certainty, but without precision; Experiment adds nothing to the certainty, but renders the fact precise, and quantitatively appreciable.


 * Experiment is an art, and demands an artist.


 * Dr. Whewell... in the section on the "Cause of the failure of the Greek Philosophy" in his History... first points out the common error of supposing that this cause lay in neglect of facts. The Greeks, he assures us, did not disregard experience, did not spin their philosophy purely from their own minds. "The disregard of experience is a phrase which may be so interpreted as to express almost any defect of philosophic method, since coincidence with experience is requisite to all theory." He adds that Aristotle not only insisted on experience as the foundation of science, but "also stated in language much resembling the habitual phraseology of modern schools that particular facts must be collected; that from these, general principles must be obtained by induction; and that these principles, when of the most general kind, are axioms"...Dr. Whewell concludes that "the defect was that though they had in their possession Facts and Ideas, the Ideas were not distinct and appropriate to the Facts. ...he simply says that the Facts were wrongly interpreted, not why they were so.
 * Footnote) Whewell: History of the Inductive Sciences 3rd ed., 1857, I, 54.


 * Answering this criticism [above], he [Dr. Whewell] affirms that his explanation, over and above the case of failure, points out the one special direction, out of several, in which the Greeks went wrong. "They did not fail because they neglected to observe facts; they did not fail because they had not ideas to reason from; but they failed because they had not the right ideas in each case. And as long as they were wrong in this point, no industry in collecting facts, or ingenuity in classing them and reasoning about them, could lead them to solid truth. ...the reason of Aristotle's failure in his attempts at mechanical science is that he did not refer the Facts to the appropriate Idea, namely Force, the Cause of Motion, but to relations of Space, and the like; that is he introduced geometrical instead of mechanical Ideas."


 * When the orbit of the planets was held to be circular, and their motion uniform, the appropriate and distinct Ideas of Space and Time were not less vividly present to the mind of Aristotle, than they were to the mind of Kepler, when he held the orbit to be elliptical, and the motion variable.


 * Aristotle's failure in Biology is not less conspicuous than his failure in Mechanics; yet the ideas of Final Cause, Likeness, and Vitality, which are said to be the ideas appropriate to this science, were assuredly possessed by him with a distinctness unsurpassed in modern times.
 * also see Teleology.


 * Many glaring errors of the Greeks will have to be noticed... few of them can be referred to the cause assigned by Dr. Whewell.


 * The appropriate Ideas said to determine the progress of discovery are... themselves perfected—brought into distinctness—during the progress of discovery, and cannot properly be applied as Instruments until some progress has been achieved.


 * It is true that they [the Greeks] observed; it is not true that they observed adequately. It is true that they invoked experience; it is not true that they invoked it sufficiently. They very imperfectly appreciated the nature of evidence; they were careless both as to the quantity and quality of the facts. ...They observed and reasoned, but observed badly, and reasoned precipitately.


 * There are three modes of investigation: Observation, Induction, Deduction. To be fruitful these must all be rigorously subordinated to Verification. ...At any one of these stages error may creep in ...Imperfectly observed facts, imperfect inductions and deductions, constantly betray men of science in our own day; and more constantly betrayed the Greeks, because the Greeks were less alive to the dangers.


 * Our sole superiority consists in this: we have an ampler basis of demonstrated and colligated truths, and a keener sense of the sources of error. They [the Greeks] were careless and credulous, where we are circumspect and sceptical. They were confident and precipitate in induction; and when an argument was verbally consistent it had an excellent chance of being accepted as an accurate representation of the order of nature.


 * The true [Scientific] Method came into use only after the baffled ingenuity of many generations had disclosed the futility of every other, and partial success had cheered men on the difficult but certain path.


 * The complexity of phenomena is that of a labyrinth, the paths of which cross and recross each other; one wrong turn causes the wanderer infinite perplexity. Verification is the Ariadne-thread by which the real issues may be found.


 * Unhappily, the process of Verification is slow, tedious, often difficult and deceptive; and we are by nature lazy and impatient, hating labour, eager to obtain. Hence credulity.


 * Science is the attempt to interpret the phenomena. ...But men ...will not await the tardy results of discovery; they will not sit down in avowed ignorance. Imagination supplies the deficiencies of Observation. A theoretic arch is thrown across the chasm, because men are unwilling to wait till a solid bridge be constructed.


 * Newton, with all his genius, would not have detected the law of gravitation had not Kepler and Galileo preceded him; nor could they have made their discoveries had not Greek mathematicians supplied the means.


 * The Subjective Method is co-extensive with our ignorance.


 * It is the tendency of all positive knowledge of objects gradually to displace the subjective fictions by which the blank of ignorance was at first filled up.


 * The amazing rapidity of scientific progress in the last half century, compared with the slowness of its progress in early times, is clearly due to the facilities afforded by what may be called the historical conditions—the state of knowledge out of which the progress issued.


 * The false Method is still employed, and in certain inquiries preserves its supremacy; but the existence of a vast body of scientific doctrine, and the rapidly increasing extension of the scientific spirit, prove that the true Method is at length predominant.

Ch.4 The Metaphysical and Scientific Methods

 * It is a great, though frequent error, to suppose that all metaphysical problems are beyond our power, and that many physical problems are not so. The vanity of Metaphysics lies in its Method, not in its aims.


 * The fundamental ideas of modern science are as transcendental as any of the axioms in ancient philosophy. Who will say that the Law of Causation, or the Laws of Motion, although suggested by experience, and found to be conformable with it, do not transcend it?


 * The uniformity of undisturbed rectilinear motion is an abstraction. But it is gained objectively—it is abstracted from facts accurately observed, and is verified by undeviating conformity with facts.


 * We are... brought round to the simple rule which Science inscribes on the pediment of her temple:—No formula admissible unless verifiable; none admitted, except as an hypothesis, until verified; the Verification having two different criteria: one, conformity with the positive laws of thought; the other, conformity with the observed order of phenomena.


 * No question within the sphere of natural phenomena is too vast for human capacity, or too subtle for human ingenuity, if it can be brought within the range of Verification, direct or indirect; and all questions are insoluble so long as they remain outside this range.


 * Facts are indissolubly ideal—the appearances of things to us, not the things per se, and... so far from any fact being the unadulterated image of its object, the conditions of our consciousness are necessarily mingled with it.


 * A fact may be defined as a bundle of inferences tied together by one or more sensations.


 * If.... Facts are inextricably mingled with Inferences, and if both Perception and Reasoning are processes of mental vision reinstating unapparent details, and liable to error in the inferences, it is clear that the radical antithesis is not between Fact and Theory, but between verified and unverified Inferences.


 * The same statement may be either a fact or a theory, without any change in its evidence.


 * Failing... to discover any valid antithesis between Fact and Theory, we must look upon the ordinary distinction as simply verbal. Shall we express it by the terms Description and Explanation, implying that a Fact describes the order of phenomena, and a Theory interprets that order? ...Yet on examination we shall find that an Explanation is only a fuller Description: more details are introduced, greater precision is given, the links in the chain which are unapparent to sense, are made apparent to reason; but the essential mystery is untouched; successions are enumerated, but causation escapes.


 * What is termed the explanation of a phenomenon by the discovery of its cause, is simply the completion of its description by the disclosure of some intermediate details which had escaped observation. The phenomenon is viewed under new relations. It is classed. It is no longer isolated, but linked onto known facts.


 * We learn that chlorine is a gas having a strong "tendency" to unite with hydrogen... But the tendency is only manifested in sunlight. The two gases may be mingled together in darkness, and will not there unite... Admit a ray of light, and the gases rush together with a loud explosion. So far we can describe. ...Shall we seek... a "repulsive force," which we assign to the darkness, and which would forcibly separate the two gases? On the Metaphysical Method this would be legitimate, and metaphysicists might accept the explanation. On the Scientific Method it would at once be condemned, because it does not bring the unknown into visible relation with the known, but into imaginary relation with an imagined fact. Darkness is itself a negation, and its repulsive force a fiction without basis.


 * "There is one basis of science," says Descartes, "one test and rule of truth, namely, that whatever is clearly and distinctly conceived is true." A profound psychological mistake. It is true only of formal logic, wherein the mind never quits the sphere of its first assumptions to pass out into the sphere of real existences; no sooner does the mind pass from the internal order to the external order, than the necessity of verifying the strict correspondence between the two becomes absolute. The Ideal Test must be supplemented by the Real Test, to suit the new conditions of the problem.


 * "Reason is the Absolute," says Schelling, "and all the objections against this proposition spring from our tendency to regard things, not as they are in Reason, but as they appear." Again: "It is a fundamental belief that not only do things exist independently of us, but that our Ideas so completely correspond with them that there is nothing in the things which is not in our Ideas.
 * Footnote) Schelling: Zeitsrhrift für speculative Physik, II. Heft. II., 3.


 * Hegel... scornfully characterizes Empiricism as seeking truth in Experience instead of in Thought. It is on such principles that the modern German Philosophy has reproduced the ambitious but inane attempts of Scholasticism.
 * Footnote) Hegel, Encyclopædie der philos. Wissenschaften, &#167; 37 Heidelberg, 1830, p. 44.


 * It is obvious that the truths of formal logic are unimpeachable. But they lose their guarantee in passing beyond their sphere. ...No sooner do we pass beyond the region of abstractions, than we must at every step assure ourselves of the truth of our inferences by the confirmation of reality. This necessity metaphysicians have overlooked. Logical dependence was the sole test they sought.


 * The uniform velocity of the planets was involved in the idea of their circular orbit, which again was involved in the idea of the circle as the most perfect form. The variable velocity of the planets is equally involved in the idea of their orbit being elliptical; but this idea was not gained by deduction from the idea of perfection; it was gained by an abstraction from the observed order of phenomena: it was a verifiable and verified inference. The one conclusion was purely metaphysical, the other purely scientific.


 * Unless we adopt the Platonic conception of Ideas, and suppose that our á priori notions are independent of experience, it is obvious that the Metaphysical Method violates the first principles of research. If experience is the basis of even abstract knowledge—the abstract notions being elicited from concrete facts—experience will be the test of all knowledge.


 * This is not the place to re-open the discussion respecting the origin of knowledge. Those who hold that the mind is furnished with ideas derived from a source independent of experience, and not therefore amenable to it, must nevertheless confine themselves strictly within the sphere of such ideas, and not include in it the facts only given by experience.


 * Descartes, who started from universal doubt, refusing to admit anything but what was demonstrably true, very soon wandered into error, because his criterion of truth was simply subjective... What he can easily conceive, he at once unsuspectingly accepts to be the truth; any confirmation of this view by the application of the Real Test he deems superfluous. Here, as throughout, he falls into the common mistake of metaphysicians.
 * Footnote) Descartes, Traité des Passions, art. 32. (Euvres, ed. Simon: Paris 1844 p. 519.


 * Kant truly says "it is the fate of human reason in speculation to build as rapidly as possible, and only when the edifice is completed to examine the solidity of its foundations." And the source of such carelessness he finds in this, that [from] knowledge often consisting in the analysis of our conceptions, we are led to pay exclusive attention to them, rather than to their origin.
 * Footnote) Kant, Kritik Einleitung, &#167; III., p. 9.


 * A theory may be transferred from Metaphysics to Science, or from Science to Metaphysics, simply by the addition or the withdrawal of its verifiable element.


 * The law of universal attraction becomes pure Metaphysics if we withdraw from it the verifiable specification of its mode of operation. Withdraw the formula "inversely as the square of the distance and directly as the mass," and Attraction is left standing a mere "occult quality." Indeed the Cartesians reproached it with being such an occult quality and stigmatized it as a revival of Aristotelianism. On the other hand, add this verifiable formula to the "inherent virtue" of the old metaphysicists, and the result is a strictly scientific proposition.


 * How is... transference from Metaphysics to Science effected? Obviously by the precision of our description, the intercalation of facts in their proper order, facts which previously had been unsuspected, or had not been seen in that order.


 * It is a common mistake to suppose that Science deals solely with facts, and Metaphysics with ideas. Both deal largely with both. The difference lies in the authenticity of the Method by which the facts are collected, and coordinated.


 * There is abundance of well authenticated facts which nevertheless form no Science because their co-ordination has not been effected; they are bricks awaiting the architect.


 * The spontaneous tendency to invoke a Final Cause in explanation of every difficulty is characteristic of metaphysical philosophy. It arises from a general tendency towards the impersonation of abstractions which is visible throughout History.


 * We animate Nature with intentions like our own... impersonate the causes as Deities; we next eliminate more and more of the personal elements, leaving only abstract Entities; we finally reduce these Entities to Forces, as the general expression of Properties or Relations, e.g., the Force of gravity is only the abstract expression of the fundamental relation which matter universally manifests.


 * We can conceive that what we imagine to be a Vital Principle, anterior and independent in the organism, is really nothing but our generalized expression, abstracted from the mutually dependent facts. It is the same with all the other numerous impersonations of abstract ideas. They are collected from the observed order, and interpreted according to the analogies of our personality; then the facts from which they were abstracted are gradually dropped out of sight, until only the abstraction remains. When this has been done, we have great difficulty in not believing that they exist independently of the facts—that our subjective separation corresponds with an objective separation—and we therefore make them the starting-points of investigation without reference to the facts. This is the basis of Metaphysics.


 * We may now glance at the influence of Language in abetting the spontaneous tendency... "...the method of real inquiry was the way to success, but the Greeks followed the... verbal or notional course, and failed." Not the Greeks alone, but all metaphysicians, metaphysicists, and metaphysiologists, have followed this course... when they have once adopted the belief that the order in ideas necessarily represents the order in external things. The pivot of Science is precisely the Verification of this assumed correspondence.
 * Footnote) Whewell, History of the Inductive Sciences 1857, I., 27.


 * Aiding and abetting this tendency in the mind to accept ideas as exact representations of things, there is the tendency to assume that distinct names represent distinct facts, so that to analyse the meaning of words is held equivalent to analysis of the things represented. Psychology has made a great advance when it has learned to question these primitive assumptions, an advance which was scarcely suspected in ancient philosophy. The theory of Language was little understood, and nations familiar with no language but their own could hardly have been on their guard against verbal fallacies.


 * In passing from formal logic to physical inquiry, a new set of conditions is entered upon, and the test of conformity with fact becomes imperative.


 * There has of late years arisen a desire to banish the word "cause" from inductive philosophy; but the word is useful, and it cannot be banished. All that can be done is to mark out clearly the meaning assigned to it in science, namely that of unconditional antecedence. The metaphysical conception of a cause, the producer of effect, needs limitation. We can know nothing of the final nexus.


 * We must limit even the conception of necessary sequence, which is held to express all that is known of causation. There is no following of effects from causes; but as Sir John Herschel more truly says, the causes and effects are simultaneous.


 * Bring a magnet within a certain distance of a needle and the needle rushes towards it. Here the magnet is said to produce motion. ...But however indispensable, such language is merely an artifice. No separation actually exists. There is not first attraction, and subsequently motion; the two are simultaneous. In like manner, we say the earth's attraction causes the weight of the apple; but the weight is the attraction: they are two aspects of one unknown reality.


 * Science... recognizes the constant presence of the Unknowable, as something real though inaccessible; but while admitting the mystery it makes no effort to transcend the already vast limits of the Knowable.


 * So readily does it [Science] restrict itself within the relative and phenomenal that it accepts hypotheses which are themselves unverifiable and which even seem absurd if in any way they facilitate the more accurate co-ordination of facts. This is a paradox but it is significant. The first person who grasped its significance I believe to be Copernicus. In the preface to his immortal work he says of the heliocentric hypothesis, "It is by no means necessary that hypotheses should be true, nor even seem true, it is enough if they reconcile calculation with observation."


 * So indifferent is Science to the absolute truth of ideas; so anxious about their relative truth! The reverse is the case with Metaphysics. It cannot be indifferent to absolute truth; if its ideas are false, all deductions drawn from them are vitiated.


 * Metaphysics is the co-ordination of unverified facts. Science is the co-ordination of verified facts. That confirmation which the one sees in Logic, the other sees in Observation. The metaphysical tendency is the spontaneous tendency; the scientific caution is an acquired caution.


 * No one who scrutinizes the science of our day can fail to perceive how ready men still are to accept phrases for explanations, and guesses for facts.


 * I have thus endeavoured to make clear the characteristics and defects of the Metaphysical Method in contrast with the characteristics of the Scientific Method, and shall have frequent opportunities... of invoking and illustrating what may be called the supreme law of all research—the principle of Verification. ...The principles of Inductive and Syllogistic Logic have indeed been amply expounded [historically]; but the supreme law (with its two criteria, Ideal and Real) has been taken for granted rather than articulately expressed, and has very often been wholly overlooked.

Ch.5 Plato's Method

 * Respect often degenerates into servility because... the admiration of the few becomes the exaggeration of the many...


 * We have to consider him [ Plato ] solely with reference to Science; an aspect, it must be confessed, in which he is seen to great disadvantage.


 * To his [Plato's] great disappointment, he found Anaxagoras adducing simple physical reasons, instead of the teleological reasons, which he had expected. Such a teacher could no longer allure him.


 * In... frank avowal of the Subjective Method he [Plato] takes no precautions and offers no guarantee for the solidity of the grounds upon which he judges one reason to be stronger than another. Between the caprices of imagination and the rigours of demonstration he offers no criterion. And the disastrous consequences of this oversight are visible in every page of the Timeeus, where the idea of a Best, to which Nature is made to conform, leads him into extravagances such as would be incredible unless their origin were known.


 * Even a great intellect may unsuspectingly wander into absurdities, when it quits the firm though laborious path of inductive inquiry.


 * "The dove cleaving the thin air," to use the happy illustration of Kant, "and feeling its resistance, might suppose that in airless space her movements would be more rapid. Precisely in this way Plato thought that by abandoning the sensuous world, because of the limits it placed to his understanding, he might more successfully venture into the void space of pure intellect."
 * Footnote) Kant, Kritik Einleitung, &#167; III., 1790, p. 8.


 * It is not in Science only that Plato is misled by his Method. The same confidence in deduction from unverified premisses vitiates his teaching in every other department of inquiry, moral and political; but in Science his errors are more patent, because his statements admit of a readier, and less equivocal, confrontation with fact.

Ch.6 Aristotle's Method

 * Aristotle may be truly styled the father of the Inductive Philosophy, since he first announced its leading principles; and announced them with a completeness and precision not surpassed by Bacon himself.


 * Common to all the systematic expositions of Method that have yet been published... is the absence of the due recognition of Verification. All writers implicitly recognize Verification as the inseparable attendant of Observation, Induction, and Deduction; but they do not explicitly, and emphatically, assign to it the primary importance it should have; they do not trace in its neglect the cause of every failure. Overlooking this defect, men have expressed surprise at the unquestionable fact that Aristotle and Bacon failed egregiously in scientific research, in spite of their conception of scientific Method...


 * In direct opposition to Plato, who, denying the validity of the senses, made intuitions the ground of all true knowledge, Aristotle sought his basis in sensuous perception. Anticipating Bacon, he affirmed that it was wiser to dissect the complex phenomena of sense than to resolve them into abstractions.
 * Footnote) Bacon, Nov. Org., 41.


 * Plato held that the deceptions of sense justified scepticism of all sense-knowledge... Aristotle, more correctly, taught that error did not arise from the senses being false media, but from the wrong interpretations we put on their testimony. Manifold deceptions may thence arise; but each sense speaks truly so far as it speaks at all. It is from sense we gain the knowledge of particulars. It is from Induction we gain the knowledge of universals. Agreeing with Plato that Science is only concerned with universals, he affirmed that these could only be reached through Experience. This is the corner stone of the experience-philosophy or "Empiricism," so often urged as a reproach against Aristotle.
 * Footnote) De Anima, III., 3; Metaph. IV., 5; and elsewhere.


 * Unhappily, even by Aristotle, experience was too frequently neglected and too carelessly interrogated. The vigilance of scientific scepticism was wanting. Yet at times he seems thoroughly impressed with the necessity of securing his basis before attempting to build. "Let us first understand the facts, and then we may seek for their causes."
 * Footnote) Aristotle, De Part., I., 1, 639.


 * "The reason why men do not sufficiently attend to the facts is their want of experience. Hence those accustomed to physical inquiries are more competent to lay down the principles which have an extensive application; whereas others who have been accustomed to many assumptions without the confrontation of reality, easily lay down principles, because they take few things into consideration. It is easy to distinguish those who argue from facts and those who argue from notions."
 * Footnote Aristotle, De Gen. et Corr., I., 2, 316. Compare also De Partibus IV., 5, 679.


 * In indicating the way we are to arrive at general truths, he expresses himself with a precision unsurpassed by moderns. "We must not," he says, "accept a general principle from logic only, but must prove its application to each fact, for it is in facts that we must seek general principles, and these must always accord with the facts."
 * Aristotle, De Animal. motione, I., 698.


 * Since... it appears that Aristotle very distinctly recognized the cardinal principles of the Baconian philosophy, why... has the world credited Bacon with a great reform in the very attacks he made on Aristotle? The answer is simple. Bacon did not attack the Method which Aristotle taught; indeed, he was very imperfectly acquainted with it. He attacked the Method which the followers of Aristotle practised.


 * Hypothesis, like everything else, must be proved, or held as a mere thread, which for convenience sake may tie the facts together until a better be discovered. It must never form a basis of deduction. This Aristotle did not distinctly understand, although he is said to have invented the theory of proof.


 * If the question be asked why we must seek this proof of what has already been perceived, Aristotle answers: "Because only particulars can be perceived, and science is of universals." ...out of numerous particulars the universal becomes evident. But, he adds, the universal has the preference, because it makes evident the cause. We do not understand a phenomenon until we can demonstrate its cause by a syllogism, showing that it necessarily follows from some general principle. Hence syllogism is the true scientific instrument; and as the syllogism proceeds from the general to the particular, it must be better known in its nature than the particulars it has to prove.


 * It is necessary to appreciate clearly this distinction between knowledge of universals and knowledge of particulars. He affirms that although sensation is the origin of all knowledge, the first ideas awakened in the soul consist of general ideas. Thus a man seeing a body at a distance has at first only the general idea of substance; on approaching nearer and... recognizing many of the particulars which distinguish it as kind... he thus gains a particular idea, in lieu of his first general idea. In this way the mind advances from the universal to the particular. The infant at first calls every man papa, and every woman mamma; afterwards it learns to discriminate individuals. The fallacy here is patent. It confounds an indefinite with a generalized conception. It is a fallacy which leavens ancient speculation.


 * In spite of his recognition of the importance of observation and induction, he conceived universals as better known than particulars. It was therefore inevitable that he should practically rely on universals to the neglect of particulars, care more about syllogisms than observations; and whenever the universals (general ideas) happened to be true, the reliance was secure. Unfortunately these universals were very often false, still oftener irrelevant; and as no criterion of their truth or relevancy was furnished by the syllogism, the reliance proved disastrous.


 * By his theory of proof he placed the Ideal Test above the Real Test: this is metaphysical. Hence in his writings we see little of the patient circumspection of Verification; we see only the impatient facility of Deduction from assumptions which have not been confronted with reality.


 * It was this which led him and all the ancients to waste so much effort in the pursuit of causes. Science was supposed to be the knowledge of causes; not the knowledge of laws, or the order of succession and co-existence, but of causes which were knowable entities.


 * The distinction between the essence of a thing and the essence of our conception of a thing had not then been admitted into philosophy.


 * [Scholsticism:] Inasmuch as change is incessant, there must be some principle of change. Nature is not self-moved; we must, therefore, assume a Prime Mover, himself immoveable.


 * [Scholsticism:] What is it which causes the harmony, regularity, and beauty of the world? Obviously a fourth cause:—The final cause... gives to every movement an aim, and a benevolent aim. The good of each and the good of all is the final cause of every change.
 * Footnote) Hermolus Barbarus: Compendium scientiæ naturalis ex Aristotele, 1547, Lib. I., p. 6.


 * It is apparent, on the most casual inspection, that no one of these [Four] causes can be verifiable; no one of them is susceptible of any stronger guarantee than that of a certain logical concordance in the assumptions we make respecting them; but inasmuch as they pass beyond the sphere of ideas, and claim to represent external realities, the Real Test is indispensable; yet it cannot be applied. Such conceptions are, therefore, utterly unscientific.


 * Even in the present day there are not wanting men of eminence who firmly uphold the validity of final causes, and believe teleological argument to be an instrument of research. This is owing to the lingering influence of the Subjective Method.


 * The Objective Method teaches that it is idle to assign a final cause, unless we believe that we have, or can have, authoritative knowledge of what actually were the Creator's intentions; and such knowledge Science modestly disclaims.


 * It [Science] endeavours to co-ordinate facts; assumptions respecting the intentions of the Creator are not verifiable; if we accept them as we accept other transcendental conceptions, they can only be an unknown quantity in our calculation.


 * The futility of the teleological argument may be seen in this, that until we have discovered the law of succession, until the facts are co-ordinated, the assumption of a final cause brings with it no illumination; and when the law has been discovered, the addition of the final cause brings no increase of knowledge.


 * By the imperfection of his Method, no less than by the condition of culture at the time, Aristotle was, therefore, practically a metaphysician, assuming without misgiving, the validity of all principles that were clear and logically consistent, no matter if they were merely verbal propositions, wholly without correspondence in fact. He argued from these principles, and only scrutinized the logical dependence of his deduction, instead of scrutinizing the principles themselves, and the verification of his conclusions.


 * Aristotle's claim to our veneration is that he produced an organon of science. It was a gigantic creation and for centuries was regarded as the perfect organon. This book it was which opened the subject, and which for centuries was thought to have closed it. We, instructed by a fuller wisdom, may point out its deficiencies, and perceive how they hampered as much as they aided true investigation.


 * His noblest title is that of Father of the Inductive Method. He first made men aware of the paramount importance of Fact, and taught them to seek explanations of phenomena on the Objective Method.


 * Roger Bacon expressed a feeling which afterwards moved many minds, when he said that if he had the power he would burn all the works of [Aristotle] the Stagirite, since the study of them was not simply loss of time, but multiplication of ignorance. Yet in spite of this outbreak every page is studded with citations from Aristotle, of whom he everywhere speaks in the highest admiration.
 * Footnote) Roger Bacon: Opus Majus, Jebb's preface, p. v.

Ch.7 Aristotle's Physics, Meteorology, and Mechanics

 * Although modern Science includes ideas not less transcendental than those included in ancient Science... As abstract expressions of the observed order of nature they are liable at any moment to be displaced in favour of expressions more accurate. They serve as guides and starting-points in research. They are not believed in as absolute existences. In ancient science they were held to be absolute existences, which it was the primary object of research to find, and which, when disclosed to the imagination, required no confrontation with reality.


 * The ancients studied phenomena to discover the realities underlying phenomena; the moderns study phenomena to detect the order of their co-existences and successions.


 * It is also noticeable that, although the ancients had formed the conception of the Indestructibility of Matter, they failed to take the step which now seems so easy, the Indestructibility of Force. Ex nihilo nihil fit [Nothing comes from nothing] was an axiom applied only to Matter. ...every one believed that force could be produced where no force pre-existed.


 * The conception of the Indestructibility of Force... is now so obvious that no physicist disputes it, whatever may be his views of the nature of Force—whether he believes it to be an Entity or a Relation.


 * All we know of motion is change of position; such changes are necessarily relative; absolute motion is therefore unknown; and consequently Rest must be equally unknown.


 * Herschel has noticed how the Stagirite obstructed the progress of astronomy by not identifying celestial with terrestrial mechanics, but laying down the principle that celestial motions were regulated by peculiar laws, thus placing them entirely without the pale of experimental research, while at the same time the progress of mechanics was impeded by the [his] assumption of natural and unnatural motions.
 * Footnote) Herschel Discourse on Natural Philosophy, 1830 (294).


 * In our day the principle [of Uniformity] is so familiar that we imagine it must have been an easy step to generalize from terrestrial to celestial mechanics. Yet neither Kepler, the bold, nor Galileo, the far seeing, had the courage to make such a generalization. Kepler assumed that there was some distinct force operating in planetary motions; and it was for the same purpose that Descartes invented his vortices. Even Newton... was very timid in extending terrestrial to celestial laws; and Auguste Comte goes so far as to consider the extension of gravitation beyond our solar system to be very rash, unless understood to be simply a conjecture founded on analogy.
 * Footnote) Comte: Cours de Philos. Positive, 1835, III., 254.


 * He who is ignorant of Motion, says Aristotle, is necessarily ignorant of all natural things. ...Not only was he entirely in the dark respecting the Laws, he was completely wrong in his conception of the nature of Motion. ...He thought that every body in motion naturally tends to rest.


 * We have learned... that Rest is only Equilibrium, and that is the action of equal and opposing forces, i.e., tension.


 * The ancients all conceived Rest as something essentially different from Motion, different in nature, not simply in quantitative amount. They believed the earth to be at rest; we... have learned to regard motion simply as a change of relation.


 * The physical writings of Aristotle still extant are the eight books of Physics, the four books On the Heavens, the two books on Generation and Corruption, with the Meteorology, and the Mechanical Problems. The sciences which we class under the heads of Physics and Astronomy are in no sense represented in them. ...There is nothing beyond metaphysical disquisitions suggested by certain physical phenomena; wearisome disputes about motion, space, infinity, and the like; verbal distinctions, loose analogies, unhesitating assumptions, inexpressibly fatiguing and unfruitful. ...We cannot say that on every point he is altogether wrong; on some points he was assuredly right; but these are few, isolated, without bearing on the rest of his speculations, and without influence on research.


 * In Book I., after briefly laying down the rules of Method, he examines the opinions of his predecessors. This has an historical interest, but science nowadays is somewhat indifferent to criticisms on Being, or the various meanings which may be attached to the word.
 * on Physics, Book I.


 * There are, he says, three principles: Matter, Form, and Privation. In every phenomenon we can distinguish the substance and its form; but as the form can only be one of two Contraries, and as only one of these two can exist at each moment, we are forced to admit the existence of a third principle—Privation—to account for the contrary which is absent. Thus a man must be either a musician or a non-musician; he cannot be both at the same time; and that which prevents his being one of these is the privation of the form.
 * on Physics, Book I.


 * Another conclusion reached, after some difficulty, is that Motion really exists.
 * on Physics, Book I.


 * In Book II. he presents his definition of Nature. After some confused and vacillating explanation, he arrives at the conclusion that Nature is the principle of Motion and Rest.
 * on Physics, Book II.


 * Those things are called natural which are self-moved. He then enters upon the four causes... These comprise Nature: for everything has substance, everything has form, everything has motion, everything has an end or aim.
 * on Physics, Book II.


 * He... argues against those who hold Chance to be a cause of phenomena. "What, it has been said, is to prevent nature from acting without an aim, and without any reference to the Best? Why should not Zeus rain from necessity, and not to make the corn grow? Since the vapour, rising upwards, must become cold, and vapour chilled is water, which would descend as rain; and, because this has happened, the corn has grown. Again, if the corn in a granary is ruined by the rain, we cannot say that the final cause of the rain was the ruin of the corn, but that this ruin was accidental. ...What then prevents the organs of animals from being formed in a similar way [above]? Those things which happen to be constituted as if they were made for an express purpose persist, and are preserved because the conditions permit; but those of which this is not the case have perished, or will perish." ...he proceeds to answer it as follows:—"That this should be the case is impossible, and for this reason: these things and all things naturally generated, are always, or mostly, so generated. On the contrary, this is never seen in spontaneous or accidental cases.
 * on Physics, Book II.


 * "If it is impossible to say the phenomena are accidental, it is clear they must occur with some end in view. But since all things are thus in nature... there must necessarily be a final cause of these things which in nature exist, or are produced." Considering the reputation of Aristotle as a logician, this is, perhaps, one of the feeblest arguments ever put forth on this subject, which has elicited many.
 * on Physics, Book II Footnote) Aristotle himself on one occasion sees through the absurdity of always seeking final causes (&#167; 401).


 * Nature is to be considered under two aspects—Matter and Form. Now form being an end, and all the rest being arranged with reference to it, we may call the form the final cause. Error, is however, possible both in Nature and in Art. A grammarian may be betrayed into an error of spelling, a physician into administering a wrong potion. Similar errors may exist in Nature.
 * on Physics, Book II.


 * In Book III. we have his celebrated definition of Motion as the passage from potential existence to actual existence. "Motion is the energy of what exists in power, so far as existing. It is the act of a moveable which belongs to its power of moving."
 * on Physics, Book III.


 * Since motion is continuity, and as such infinitely divisible; therefore the Infinite must first be studied. Then again as Motion implies both Space and Time, these also must be studied. What Aristotle has to say on these transcendental questions... would occupy too much space and too unprofitably, to reproduce it here.
 * on Physics, Book III.


 * I... call attention to the long persistence of the metaphysical fallacy which kept up discussions on such subjects as the existence of space as anything more than a relation. The fallacy is, that whenever man can form clear ideas, not in themselves contradictory, these ideas must of necessity represent truths of nature. Hence when we conceive body, we conceive it as existing in something, which contains it (i.e., body as filling space) we are led to believe that this all-container must itself have an objective existence. The idea will not withstand criticism. An equal necessity can be shown for something to contain the container. As we cannot pursue this reduction ad infinitum, we must stop somewhere; why not, therefore, stop at Substance, of which we know something, rather than go on to Space, of which we know nothing?
 * on Physics, Book III.


 * The argument of J. Bernouilli... is a specimen of metaphysical trifling quite worthy of Aristotle. "Before the creation of the world there was nothing existing, except God. If this universal vacuity was not repugnant to Creative Wisdom, we cannot suppose it repugnant to his Wisdom if there are now many vacant spaces between existing bodies." Out of similar "suppositions" and "clear ideas," metaphysicians have built many systems; systems, but no science.
 * on Physics, Book III.


 * Instead of wearying the reader with discussions about Space, let me detach from Aristotle's fourth book the theory of projectiles, interesting in itself, and also because it gives us the first glimpse of a conception of Inertia.
 * on Physics, Book IV.


 * He argues that in vacuo, Motion is impossible. In a void there can be no difference of place; and motion implies difference of place. He then adds that projectiles continue moving after the original motor ceases to be in contact with them, "either, as some say, by reaction, or by the motion of the moved air, which is more rapid than that of the natural tendency of the body to its proper place."
 * Footnote) Compare also lib. VIII., chap. X., 267. Galileo's masterly refutation of this may be seen in his Dialoghi, Giornata Seconda (Opera, Milan, 1811, XI., 344).
 * on Physics, Book IV.


 * "Moreover," he adds, "no one can say why in vacuo a body once set in motion should ever stop; since why rather here than there? Consequently it must either remain in necessary rest, or—if in motion—in endless motion, unless some stronger interferes." ...He had by no means overlooked the fact of the resistance of air, since he compares it with the resistance of water. Yet the air is made to keep up rather than destroy the motion of a projectile. He had... got a glimpse of Inertia—at least, as regards bodies in vacuo. But it never occurred to him to connect the two ideas, and make inertia keep up the continuity of motion, and resistance of the air destroy the motion.
 * Footnote) As Des Cartes did. See his Principia Philos. pars II., c. xxxviii.


 * He was forced to seek for some continuous external motor to account for continuous motion; "the pulses of the moved air" was the first cause which presented itself, and was accepted at once. Whereas had he (and succeeding philosophers) steadily conceived the so-called Law of Inertia—that is to say, the transcendental Law of Causation, that every change demands a cause,—he would have perceived that continuous motion was motion unchanged—would have perceived that no external cause was needed for such continuity, but was only needed to arrest, deflect, accelerate, in a word change the motion. The pulses of air might thus have been conceived as retarding the motion, deflecting it, or accelerating it—and by Verification he would have ascertained which of these conceptions was correct. But in no sense could the pulses of air have been conceived as causing the simple continuance of motion, since continuance implied that there was nothing to cause change.
 * on Physics, Book IV.


 * The succeeding Books (V. VIII.) are mainly devoted to Motion. It is divided into absolute, partial, and accidental motions—phrases much cherished by scholasticism, which fed on phrases as the fabled chamæleon fed on air.
 * on Physics, Books V-VIII.


 * In the theory of motion five elements are involved: the motor, the moved, the direction of movement, the starting point, and the goal. It is from the last that motion receives its special designation. Thus the corruption of a body is its movement towards non-existence, although it must necessarily start from existence. In like manner the movement of generation is a movement towards existence, though starting from non-existence. ...how fertile such principles must have been in verbal disputation, how sterile in any other result. Yet this is the system which has been compared with Newton's!
 * on Physics, Books V-VIII.


 * There are three Categories of Motion laid down:—1. Quantity; 2. Quality; 3. Place. On these he rings the changes. When a body increases or diminishes, there is the motion of quantity. When the body changes its quality without changing its quantity—as in becoming hot or cold—there is the motion of quality. When a body merely changes its place, there is locomotion, or the "motion of place."
 * on Physics, Books V-VIII.


 * There are two great classes of movements—1st, the natural; and 2nd, the violent, or unnatural. ...Fire ascends, and a stone descends, by natural movement. A stone may be made to ascend, but this is owing to violence; some external motor causes it to ascend; by its natural movement the stone would never rise, but always fall. For a similar reason fire may be made to descend; but left to its natural movement it will only ascend.


 * Translation being the first of movements, and being reducible to circular, linear, and mixed, the question arises: Which of these is the most perfect? which represents the infinite, continuous, uniform motion of the First Mover? Not the mixed, since that is a combination of the two others. Not the linear, since a straight line is necessarily finite, and if a body were to move eternally along it, there must be a return, which would produce contrary movements, and moments of repose, which would be solutions of continuity. The circular therefore alone remains: in the circle there is no solution of continuity: the motion may be eternal in it. This demonstration of circular movement as the most perfect, played a conspicuous part in peripatetic philosophy. Yet the reader sees at once how entirely it is removed from reality, how purely verbal its basis, how utterly unscientific. The same may be said of all the ideas expounded in the Physics; and we need bestow no more time upon them.