and classification. And along with the incapacity for framing new theories there arose a desire to diminish the number of those already existing, to frame, if possible, a system which should select and combine whatever was good in any or all of them.

VII.

This, then, was the revolution effected by Aristotle, that he found Greek thought in the form of a solid, and unrolled into a surface of the utmost possible tenuity, transparency, and extension. In so doing, he completed what Socrates and Plato had begun, he paralleled the course already described by Greek poetry, and he offered the first example of what since then has more than once recurred in the history of philosophy. It was thus that the residual substance of Locke and Berkeley was resolved into phenomenal succession by Hume. It was thus that the unexplained reality of Kant and Fichte was drawn out into a play of logical relations by Hegel. And, if we may venture on a forecast of the future towards which speculation is now advancing, it is thus that the limits imposed on human knowledge by positivists and agnostics in our own day, are yielding to the criticism of those who wish to establish either a perfect identity or a perfect equation between consciousness and being. This is the position represented in France by M. Taine, a thinker offering many points of resemblance to Aristotle, which it would be interesting to work out had we space at our command for the purpose. The forces which are now guiding English philosophy in an analogous direction have hitherto escaped observation on account of their disunion among themselves, and their intermixture with others of a different character. But on the whole we may say that the philosophy of Mill and his school corresponds very nearly in its practical idealism to Plato's teaching; that Mr. Herbert Spencer approaches

Aristotle on the side of theorising systematisation, while sharing to a more limited extent the metaphysical and political realism which accompanied it; that Lewes was carrying the same transformation a step further in his unfinished Problems of Life and Mind; that the philosophy of Mr. Shadworth Hodgson is marked by the same spirit of actuality, though not without a vista of multitudinous possibilities in the background; that the Neo-Hegelian school are trying to do over again for us what their master did in Germany; and that the lamented Professor Clifford had already given promise of one more great attempt to widen the area of our possible experience into co-extension with the whole domain of Nature.'1

The systematising power of Aristotle, his faculty for bringing the isolated parts of a surface into co-ordination and continuity, is apparent even in those sciences with whose material truths he was utterly unacquainted. Apart from the falseness of their fundamental assumptions, his scientific treatises are, for their time, masterpieces of method. In this respect they far surpass his moral and metaphysical works, and they are also written in a much more vigorous style, occasionally even rising into eloquence. He evidently moves with much more assurance on the solid ground of external nature than in the cloudland of Platonic dialectics, or among the possibilities of an ideal morality. If, for example, we open his Physics, we shall find such notions as Causation, Infinity, Matter, Space, Time, Motion, and Force, for the first time in history separately discussed, defined, and made the foundation of natural philosophy. The treatise On the Heavens very properly regards the celestial movements as a purely mechanical problem, and strives throughout to bring theory and practice

Cf. the memorable declaration of Mr. F. Pollock: To me it amounts to a contradiction in terms to speak of unknowable existence or unknowable reality in an absolute sense. I cannot tell what existence means if not the possibility of being known or perceived.'--Spinoza, p. 163.

into complete agreement. While directly contradicting the truths of modern astronomy, it stands on the same ground with them; and anyone who had mastered it would be far better prepared to receive those truths than if he were only acquainted with such a work as Plato's Timaeus. The remaining portions of Aristotle's scientific encyclopaedia follow in perfect logical order, and correspond very nearly to Auguste Comte's classification, if, indeed, they did not directly or indirectly suggest it. We cannot, however, view the labours of Aristotle with unmixed satisfaction until he comes on to deal with the provinces of natural history, comparative anatomy, and comparative psychology. Here, as we have shown, the subject exactly suited the comprehensive observation and systematising formalism in which he excelled. Here, accordingly, not only the method but the matter of his teaching is good. In theorising about the causes of phenomena he was behind the best science of his age; in dissecting the phenomena themselves he was far before it. Of course very much of what he tells was learned at secondhand, and some of it is not authentic. But to collect such masses of information from the reports of uneducated hunters, fishermen, grooms, shepherds, beemasters, and the like, required an extraordinary power of putting pertinent questions, such as could only be acquired in the school of Socratic dialectic. Nor should we omit to notice the vivid intelligence which enabled even ordinary Greeks to supply him with the facts required for his generalisations. But some of his most important researches must be entirely original. For instance, he must have traced the development of the embryo chicken with his own eyes; and, here, we have it on good authority that his observations are remarkable for their accuracy, in a field where accuracy, according to Caspar Friedrich Wolff, is almost impossible.'

Aristoteles von d. Zeugung u. Entwickelung d. Thiere. Aubert u. Wimmer, Einleitung, p. 15.

Still more important than these observations themselves is the great truth he derives from them-since rediscovered and worked out in detail by Von Baer-that in the development of each individual the generic characters make their appearance before the specific characters. Nor is this a mere accidental or isolated remark, but, as we shall show in the next chapter, intimately connected with one of the philosopher's metaphysical theories. Although not an evolutionist, he has made other contributions to biology, the importance of which has been first realised in the light of the evolution theory. Thus he notices the antagonism between individuation and reproduction; the connexion of increased size with increased vitality; the connexion of greater mobility, and of greater intelligence," with increased complexity of structure; the physiological division of labour in the higher animals; the formation of heterogeneous organs out of homogeneous tissues; the tendency towards greater centralisation in the higher organisms a remark connected with his two great anatomical discoveries, the central position of the heart in the vascular system, and the possession of a backbone by all red-blooded animals; the resemblance of animal intelligence to a rudimentary human intelligence, especially as manifested in children; 10 and, finally, he attempts to trace a continuous series of gradations connecting the inorganic with the organic world, plants with animals, and the lower animals with man."

9

The last mentioned principle gives one more illustration of the distinction between Aristotle's system and that of the evolutionist, properly so called. The continuity recognised

De Gen. An., II., iii., 736, b, 1.
De Respir., 477, a, 18.

Ibid., II., x., 656, a, 4.

2 Ibid., I., xviii., 725, b, 25.
De Part. An., I., vii., sub. in.

• Ibid., IV., vi., 683, a, 25. ' Ibid., II., i.

Ibid., IV., v., 682, a, 8; De Long., vi., 467, a, 18; De Ingr. An., vii.,

707, a, 24.

De Part. An., II., ix., 664, b, 11; Zeller, p. 522. 10 Hist. An., VIII., i, sub in.

"Zeller, p. 553.

by the former only obtains among a number of coexisting types; it is a purely logical or ideal arrangement, facilitating the acquisition and retention of knowledge, but adding nothing to its real content. The continuity of the latter implies a causal connexion between successive types evolved from each other by the action of mechanical forces. Moreover, our modern theory, while accounting for whatever is true in Aristotle's conception, serves, at the same time, to correct its exaggeration. The totality of existing species only imperfectly fill up the interval between the highest human life and the inorganic matter from which we assume it to be derived, because they are collaterally, and not lineally, related. Probably no one of them corresponds to any less developed stage of another, although some have preserved, with more constancy than others, the features of a common parent. In diverging from a single stock (if we accept the monogenetic hypothesis,) they have become separated by considerable spaces, which the innumerable multitude of extinct species alone could fill up.

Our preliminary survey of the subject is now completed. So far, we have been engaged in studying the mind of Aristotle rather than his system of philosophy. In the next chapter we shall attempt to give a more complete account of that system in its internal organisation not less than in its relations to modern science and modern thought.