92 J. M. BIGG : retracted, and the unknowable restored to its full privilege of unknowability. But to return to Aristotle : he resumes the criticism of Empe- docles in the fifth chapter of the second book, contenting himself however with pointing out the essential distinction between the passive reception of an affection and the active response of a faculty to stimulus. In the brief chapter which follows, he anticipates Locke's distinction between the primary and second- ary qualities of matter by his division of perceptions into particular and common ; with this difference, however, that unlike Locke with his primary qualities (solidity, extension, figure, motion or rest, and number) he does not regard the common perceptions, motion, rest, number (in which, as we have seen, he includes time), figure and magnitude, as being any less relative to con- sciousness than the particular perceptions. The seventh and following chapters including the eleventh are devoted to discussing the physical conditions of the special per- ceptions and, though ingenious and interesting in themselves, are of no importance for our present purpose. At the close, however, of the eleventh chapter, Aristotle is brought back to the psycho- logical point of view by consideration of the fact that extreme intensity of sensation interferes with clearness of perception ; showing, he says, that perception is a judgment, which implies the equal presence to several sensations of a fieaov, a principle at once unifying and distinguishing that judges between them. This idea is farther developed in the twelfth chapter. In the second chapter of the third book he raises the question how it is that we are able to compare the special perceptions so as to recognise their unity as perceptions. In themselves, he seems to argue, colour and taste are neither similar nor different. How then are they comparable and distinguishable ? The answer of course is that consciousness implies a principle of unity through the common relation of which to the special perceptions the latter are at once united and distinguished. 1 In the seventh chapter this unifying principle is explicitly identified with the i-ovv. As I understand Aristotle, then, he conceived the reason to be operative in constituting the objects of perception as well as in theorising, to be eternal and homogeneous with the principle revealed to it in nature. On this latter point there is indeed no doubt. At the end of the third chapter of the first book of the Mi'fuji/ii/xtf't he makes it perfectly clear that reason is with him the reality of nature, and the same doctrine is more formally and precisely stated in the seventh and ninth chapters of the eleventh book of that treatise. It follows that a definition of the soul per (jcnus et dl/<-r<'i,1!inn is not to be looked for from him. As he says, " the soul is in a manner all things ; for things are either perceivable or intelligible, and the intelligible world exists 1 firtl 8t . . . . 8rja (Ivai (Ik An., iii. 2).
