FORE:We are now in a position to understand the full force of Descartes�� Cogito ergo sum. It expresses the substantiality of self-conscious Form, the equal claim of thought with extension to be recognised as an element of the universe. This recognition of self-consciousness as the surest reality was, indeed, far from being new. The Greek Sceptics had never gone to the length of doubting their own personal existence. On the contrary, they professed a sort of subjective idealism. Refusing to go beyond their own consciousness, they found in its undisturbed self-possession the only absolute satisfaction that life could afford. But knowledge and reality had become so intimately associated with something independent of mind, and mind itself with a mere reflection of reality, that the denial of an external world393 seemed to the vulgar a denial of existence itself. And although Aristotle had found the highest, if not the sole absolute actuality in self-thinking thought, he projected it to such a distance from human personality that its bearing on the sceptical controversy had passed unperceived. Descartes began his demonstration at the point where all the ancient systems had converged, but failed to discover in what direction the conditions of the problem required that they should be prolonged. No mistake can be greater than to regard him as the precursor of German philosophy. The latter originated quite independently of his teaching, though not perhaps of his example, in the combination of a much profounder scepticism with a much wider knowledge of dogmatic metaphysics. His method is the very reverse of true idealism. The Cogito ergo sum is not a taking up of existence into thought, but rather a conversion of thought into one particular type of existence. Now, as we have seen, all other existence was conceived as extension, and however carefully thought might be distinguished from this as absolutely indivisible, it was speedily reduced to the same general pattern of inclusion, limitation, and expansion. Whereas Kant, Fichte, and Hegel afterwards dwelt on the form of thought, Descartes attended only to its content, or to that in which it was contained. In other words, he began by considering not how he thought but what he thought and whence it came��his ideas and their supposed derivation from a higher sphere. Take, for example, his two great methods for proving the existence of God. We have in our minds the idea of a perfect being��at least Descartes professed to have such an idea in his mind,��and we, as imperfect beings, could not have originated it for ourselves. It must, therefore, have been placed there by a perfect being acting on us from without. It is here taken for granted that the mechanical equivalence between material effects and their causes must obtain in a world where spatial relations, and therefore measurement, are presumably394 unknown. And, secondly, existence, as a perfection, is involved in the idea of a perfect being; therefore such a being can only be conceived as existing. Here there seems to be a confused notion that because the properties of a geometrical figure can be deduced from its definition, therefore the existence of something more than a simple idea can be deduced from the definition of that idea itself. But besides the mathematical influence, there was evidently a Platonic influence at work; and one is reminded of Plato��s argument that the soul cannot die because it participates in the idea of life. Such fallacies were impossible so long as Aristotle��s logic continued to be carefully studied, and they gradually disappeared with its revival. Meanwhile the cat was away, and the mice used their opportunity.247

Published Aug 30.

FORE:Modern admirers of Aristotle labour to prove that his errors were inevitable, and belonged more to his age than to himself; that without the mechanical appliances of modern times science could not be cultivated with any hope of success. But what are we to say when we find that on one point after another the true explanation had already been surmised by Aristotle��s predecessors or contemporaries, only to be scornfully rejected by Aristotle himself? Their hypotheses may often have been very imperfect, and supported by insufficient evidence; but it must have been something more than chance which always led him wrong when they were so often right. To begin with, the infinity of space is not even now, nor will it ever be, established by improved instruments of observation and measurement; it is deduced by a very simple process of reasoning, of which Democritus and others were capable, while Aristotle apparently was not. He rejects the idea because it is inconsistent with certain very arbitrary assumptions and definitions of his own, whereas he should have313 rejected them because they were inconsistent with it. He further rejects the idea of a vacuum, and with it the atomic theory, entirely on �� priori grounds, although, even in the then existing state of knowledge, atomism explained various phenomena in a perfectly rational manner which he could only explain by unmeaning or nonsensical phrases.195 It had been already maintained, in his time, that the apparent movements of the heavenly bodies were due to the rotation of the earth on its own axis.196 Had Aristotle accepted this theory one can imagine how highly his sagacity would have been extolled. We may, therefore, fairly take his rejection of it as a proof of blind adherence to old-fashioned opinions. When he argues that none of the heavenly bodies rotate, because we can see that the moon does not, as is evident from her always turning the same side to us,197 nothing is needed but the simplest mathematics to demonstrate the fallacy of his reasoning. Others had surmised that the Milky Way was a collection of stars, and that comets were bodies of the same nature as planets. Aristotle is satisfied that both are appearances like meteors, and the aurora borealis��caused by the friction of our atmosphere against the solid aether above it. A similar origin is ascribed to the heat and light derived from the sun and stars; for it would be derogatory to the dignity of those luminaries to suppose, with Anaxagoras, that they are formed of anything so familiar and perishable as fire. On the contrary, they consist of pure aether like the spheres on which they are fixed as protuberances; though314 how such an arrangement can co-exist with absolute contact between each sphere and that next below it, or how the effects of friction could be transmitted through such enormous thicknesses of solid crystal, is left unexplained.198 By a happy anticipation of Roemer, Empedocles conjectured that the transmission of light occupied a certain time: Aristotle declares it to be instantaneous.199Jeff shook his head.

Published Aug 28.