NOTES ON AKISTOTLE'S PSYCHOLOGY. 91 upon his own theory. Empedocles held that perception is rendered possible by the presence in the soul of the same elements as are found in nature, to which Aristotle replies in effect that the mere presence of the elements in the soul would be useless in the absence of a synthetic principle, otherwise the elements might indeed be perceived in their severalty, but no concrete object could be perceived at all, and this synthetic principle can be no other than reason. 1 Here it should be observed that, crude as was the theory of Empedocles, it at any rate evinced a juster appreciation of the nature of the problem to be solved than either that of Locke or that of Mr. Herbert Spencer. Locke reflecting on the mind in its supposed pristine state of vacuity inquires how came it by its manifold content, and answers " in one word from experience ". " Our observation," he says, " employed either about external sensible objects or about the internal operations of our minds perceived and reflected on by ourselves is that which supplies our understandings with all the materials of thinking ". 2 In other words, he assumes that the mind can and does bridge the gulf which separates it from "external objects"; he assumes that these objects are " sensible," that they somehow affect the mind. The assumption however. conceals a very real difficulty and one which, though ignored by Locke, was present to the mind of Empedocles. That a material object being homogeneous with the physical organism may induce certain changes therein which ultimately issue in certain excitements of the sensorium is intelligible, but there the intelligibility stops. That the said nerve-changes should become sensations is in no way intelligible, since there is no community between a nerve-change and a sensation. The transmutation of a nerve-change into a sensation would be an uncaused event, and the assumption of an uncaused event might seem to be a bad beginning for philosophy. Yet this is just what Locke assumes. 3 Mr. Spencer attempts to evade the difficulty by describing feeling and nerve-change as two mani- festations of the same reality, that reality being assumed to be totally distinct in nature from either of its manifestations. This theory will not bear the slightest inspection. In place of explain- ing the facts it formulates them in such a manner as to preclude explanation. That the " ultimate reality " manifests itself in two phenomena totally unlike itself is a contradiction in terms. To manifest is to make known : that the unknowable makes itself known is a contradiction in terms, but when it is added that its phenomena are totally unlike itself the original statement is f )v fifv ovv .... raiv OVTWV flvai (I)& An., i. 5). " Essay concerning Human Understanding, ii. 1, 2. 3 It is but fair to Locke to observe that the difficulty becomes very real to him at a later stage (iv. 3, 28).
