dence of direct filiation; and he has studied the history of speculation to little purpose who is not thoroughly familiar with the natural tendency of the mind to sweep into the same tracks, where others have been before, where others will find themselves afterwards. Moreover, many of these coincidences, upon which historical theories are based, turn out, on close inspection, to be merely verbal, or at the best, approximative. Thus the physical speculations of the Greeks often coincide in expression with those of modern science. Does this prove that the moderns borrowed their science from the ancients? M. Dutens thought so, and has written an erudite but singularly erroneous book to prove it. Democritus asserted the Milky Way to be only a cluster of stars; but the assertion was a mere guess, wholly without proof, and gained no acceptance. It was Galileo who discovered what Democritus guessed. Thus also Empedocles, Pythagoras, and Plato, are said to have been perfectly acquainted with the doctrine of gravitation; and this absurdity is made delusive by dint of forced translations, which elicit something like coincidence of expression, although every competent person detects the want of coincidence in the ideas.*

Waiving all discussion of disputable and disputed points, it is enough that in Greece from the time of Thales, and in Europe from the time of Descartes, a regular development of Philosophy is traceable, quite sufficient for our purpose, which is less that of narrating the lives and expounding the opinions of various thinkers, than of showing how the course of speculation necessarily brought about that radical change in Method which distinguishes Philosophy from Science. In pursuance of such an aim it was perfectly needless to include any detailed narrative of the speculations which, under the name of Scholasticism, occupied the philosophical activity of the Middle Ages. Those speculations were either subordinate to Theology, or were only instrumental in perfecting philosophical language; and in this latter respect the historian of Philosophy is no more called upon to notice them, than a writer on the art of War would be called upon to

* Karsten expresses the distinction well: "Empedocles poeticè adumbravit idem quod tot seculis postea mathematicis rationibus demonstratum est à Newtono.”—Philos. Græcorum Operum Reliquiæ, p. xii.

give a history of the armorers of Milan or the sword-manufacturers of Toledo.

The same principle which determines the selection of Epochs also determines the selection of the points of doctrine to be expounded. It is obvious that in nothing like the space to which this work is limited could even the barest outline of all the opinions held by all the philosophers be crowded; nor would ten times the space suffice for an exposition of those opinions with any thing like requisite detail. Brucker's vast compilation, and Ritter's laborious volumes, are open for any student desirous of more detailed knowledge; but even they are imperfect. My purpose is different; I write. the Biography, not the Annals of Philosophy, and I am more concerned about the doctrines peculiar to each thinker than about those held by him in common with others. If I can ascertain and make intelligible the doctrines which formed the additions of each thinker to the previous stock, and which helped the evolution of certain germs of philosophy, collateral opinions will need only such mention as is necessary to make the whole course of speculation intelligible. Thus limited in scope, I may find myself more at ease in the discussion of those points on which attention should be fastened. More space can be given to fundamental topics. In restricting myself to Descartes, Spinoza, and Kant, without noticing Cartesians, Spinozists, and Kantians, I also on the same principle restrict myself to what is in each thinker peculiar to him, and directly allied to the course of philosophical development. The student who needs the Pandects of Philosophy will have to look elsewhere this work only pretends to be a Summary.

FIRST EPOCH.

SPECULATIONS ON THE NATURE OF THE UNIVERSE.

CHAPTER I.

THE PHYSICISTS.

§ I. THALES.

ALTHOUGH the events of his life, no less than the precise doctrines of his philosophy, are shrouded in mystery, and belong to the domain of fable, nevertheless Thales is very justly considered as the father of Greek Speculation. He made an epoch. He laid the foundation-stone of Greek philosophy. The step he took was small, but it was decisive. Accordingly, although nothing but a few of his tenets remain, and those tenets fragmentary and incoherent, we know enough of the general tendency of his doctrines to speak of him with some degree of certitude.

Thales was born at Miletus, a Greek colony in Asia Minor. The date of his birth is extremely doubtful; but the first year of the 36th Olympiad (B. c. 636) is generally accepted as correct. He belonged to one of the most illustrious families of Phoenicia, and took a conspicuous part in all the political affairs of his country, a part which earned for him the highest esteem of his fellow-citizens. His immense activity in politics has been denied by later writers, as inconsistent with the tradition, countenanced by Plato, of his having spent a life of solitude and meditation; while on the other hand his affection for solitude has been questioned on the ground of his political activity. It seems to us that the two things are perfectly compatible. Meditation does

not necessarily unfit a man for action; nor does an active life absorb all his time, leaving him none for meditation. The wise man will strengthen himself by meditation before he acts; and he will act, to test the truth of his opinions.

Miletus was one of the most flourishing Greek colonies; and at the period we are now speaking of, before either a Persian or a Lydian yoke had crushed the energies of its population, it was a fine scene for the development of mental energies. Its commerce both by sea and land was immense. Its political constitution afforded the finest opportunities for individual development. Thales both by birth and education would naturally be fixed there, and would not travel into Egypt and Crete for the prosecution of his studies, as some maintain, although upon no sufficient authority. The only ground for the conjecture is the fact of Thales being a proficient in mathematical knowledge; and from very early times, as we see in Herodotus, it was the fashion. to derive the origin of almost every branch of knowledge from Egypt. So little consistency is there however in this narrative of his voyages, that he is said to have astonished the Egyptians by showing them how to measure the height of their pyramids by their shadows. A nation so easily astonished by one of the simplest of mathematical problems could have had little to teach. Perhaps the strongest proof that he never travelled into Egyptor that, if he travelled there, he never came into communication with the priests--is the absence of all trace, however slight, of any Egyptian doctrine in the philosophy of Thales which he might not have found equally well at home.

The distinctive characteristic of the Ionian School, in its first period, was its inquiry into the constitution of the universe. Thales opened this inquiry. It is commonly said: "Thales taught that the principle of all things was water." On a first glance, this will perhaps appear a mere extravagance. A smile of pity may greet it, accompanied by a reflection on the smiler's part, of the unlikelihood of his ever believing such an absurdity. But the serious student will be slow to accuse his predecessors of

sheer and transparent absurdity. The history of Philosophy may be the history of errors; it is not a history of follies. All the systems which have gained acceptance have had a pregnant meaning, or they would not have been accepted. The meaning was proportionate to the opinions of the epoch, and as such is worth penetrating. Thales was one of the most extraordinary men that ever lived, and produced an extraordinary revolution. Such a man was not likely to have enunciated a philosophical thought which any child might have refuted. There was deep meaning in the thought, to him at least. Above all, there was deep meaning in the attempt to discover the origin of things. Let us endeavor to penetrate the meaning of his thought; let us see if we cannot in some shape trace its rise and growth in his mind.

It is characteristic of philosophical minds to reduce all imaginable diversities to one principle. As it is the inevitable tendency of religious speculation to reduce polytheism to monotheism, to generalize all the supernatural powers into one expression, so also was it the tendency of early philosophical speculation to reduce all possible modes of existence into one generalization of Existence itself.

Thales, speculating on the constitution of the universe, could not but strive to discover the one principle-the primary Factthe substance, of which all special existences were but the modes. Seeing around him constant transformations—birth and death, change of shape, of size, and of mode of existence-he could not regard any one of these variable states.of existence as Existence itself. He therefore asked himself, What is that invariable Existence of which these are the variable states? In a word, What is the beginning of things?

To ask this question was to open the era of philosophical inquiry. Hitherto men had contented themselves with accepting the world as they found it; with believing what they saw; and with adoring what they could not see.

Thales felt that there was a vital question to be answered relative to the beginning of things. He looked around him, and