It is probably to this notion of otherness (grepov); that we must look for a means of understanding the non-being which Plato was wont to regard as characteristic of what is phenomenal. For by non-being, we do not denote the absolute opposite (ivavrioP) of being, mere nothingness, but that which is the other of being, that which is different from it. The entire realm of Ideas is, in fact, interpenetrated by the form of otherness. Furthermore, in the Timaeus the necessity is insisted upon of recognising, besides Ideas and phenomena, a third entity which, while affording a place for all that comes into being, is itself eternal. This third element, described as the receptacle (inroaoxii) of all becoming, is identified with space; and space would seem to be contemplated as the very essence of otherness, or of difference. In itself, it is abso lutely void and formless ; it is not that out of which but that in which things become.
In short, in relation to the whole realm of Ideas, it is just the factor of non-being which according to the argument of the Sophist, is inherently involved in the notion of being. Along this line of reflection it was natural that Plato should have assigned the importance he did to the geometrical aspects of phenomena. As presented under the form of externality, an Idea is wont to appear as though it were differentiated into a multiplicity of shapes or images Kai is..Ovra) ; instead of its oneness, we get in numerable copies or likenesses of it. Not a material substratum but a figured portion of space was the basis of a physi cal thing, and that in which sense-qualities were situated.
we cannot expect more than E1K6TES XO-yot, "likely stories," under standing thereby not indeed baseless fictions but accounts that are more or less probable.
Thus the natural world is the proper object of 34a and any interpretation we can offer of its course of development must be largely pictorial or mythical in character. In a famous passage of the Republic (vi., 509 d. sqq.), Plato distinguishes four stages of cognition. There are two grades of 6OEct,—the one described as elicaola, conjecture or guess-work, the mental condition of one who accepts every presentation, so long as it lasts, as equally true with any other, and has not learned to discriminate the shadow or reflection from that which casts it ; the other described as ricrrts, conviction or assurance, the state of mind in which we are aware of what we call the actual things of the world and distin guish them from their semblances or images. A higher stage is reached when we pass from 6OEct to that grade of "knowledge" that is designated &Avoca, understanding or discursive thinking. Here the thinker is still occupied with sensible things, but he employs them as symbols of something which is not sensible. The mathematician uses diagrams and models, but what he is really thinking of is the triangle or circle as such, the "intelligible" tri angle or circle of which the "visible" one is an image. Moreover, batvota proceeds from certain assumptions or postulates which it takes as ultimate, although in truth they are in need of proof and confirmation. Hence we are led on to a cul minating stage of intelligence v6ncrLs or ircaribun, that which is aimed at by "dialectic," which has for its objects the E 16 77 them selves, and contemplates them without the aid of sensuous repre sentations.
Starting with the axioms and postulates of the previous stage, the dialectician will not treat these as ultimate, but as points of departure for advancing to a principle which is supreme and un conditional, an avvr6Ocros aPxii. The axioms and postulates of &Avoca will thus be seen to be necessary deductions from this self-evident principle. The ideal of knowledge will be attained only when reason ascends from one branch of truth to another until it reaches a truth beyond which it cannot go; and then from the cognition of it descends again to its consequences and tra verses without break the whole realm of the knowable.