[Footnote 99: The discussion in pp. 184-186-186 of the Theætêtus is interesting as the earliest attempt remaining to classify psychological phenomena. What Demokritus and others proposed with the same view--the analogy or discrepancy between [Greek: to\ ai)stha/nesthai] and [Greek: to\ noei=n]--we gather only from the brief notices of Aristotle and others. Plato considers himself to have established, that "cognition is not to be sought at all in sensible perception, but in that function, whatever it be, which is predicated of the mind when it busies itself _per se_ (_i.e._ not through any special bodily organ) about existences" (p. 187 A). We may here remark, as to the dispute between Plato and Protagoras, that Plato here does not at all escape from the region of the Relative, or from the Protagorean formula, _Homo Mensura_. He passes from Mind Percipient to Mind Cogitant; but these new Entia cogitationis (as his language implies) are still relative, though relative to the Cogitant and not to the Percipient. He reduces Mind Sentient to the narrowest functions, including only each isolated impression of one or other among the five senses. When we see a clock on the wall and hear it strike twelve--we have a visual impression of black from the hands, of white from the face, and an audible impression from each stroke. But this is all (according to Plato) which we have from sense, or which addresses itself to the sentient mind. All beyond this (according to him) is apprehended by the cogitant mind: all discrimination, comparison, and relation--such as the succession, or one, two, three, &c., of the separate impressions, the likeness of one stroke to the preceding, the contrast or dissimilarity of the black with the white--even the simplest acts of discrimination or comparison belong (in Plato's view) to mental powers beyond and apart from sense; much more, of course, apprehension of the common properties of all, and of those extreme abstractions to which we apply the words Ens and Non-Ens ([Greek: to/ t' e)pi\ pa=si koino\n kai\ to\ e)pi\ tou/tois, ô(=| to\ e)/stin e)ponoma/zeis kai\ to\ ou)k e)/stin], p. 185 C).