ON THE INTERPRETATION OF PLATO'S PARMEXIDES. 11 crease " and " decrease," it will change from motion to rest and from rest to motion (156 B). And so far, though we have not really added to our stock of knowledge about the One anything beyond what was partly implied and partly openly stated (cf. ejiyvero teal yiyverai real yevrja-erai, 155 D) in the last hypothesis, we seem to have been fairly faithful to the original subject of discussion. It is in the passage which immediately follows that Plato (156 D-157 B) suddenly introduces a new subject which is in itself of high importance though its connexion with the discussion of the One is very loose. This subject is then disposed of in a few lines and is never referred to again in the rest of the dialogue. This important and novel subject is the con- ception of an un extended temporal point, the " Instan- taneous " (TO egatyvijs) as Plato names it. We know of course from Aristotle how difficult the Greeks found it to think of a point, whether of time or of space, as having no extension, and it is, I imagine, not unlikely that this problematic conception of a moment of time which with- out having duration yet occupies a definite position in the time series was introduced into philosophy for the first time by the present passage. Plato here, as in the similar case of his tentative account of abstract space in the Timceus, marks his own sense of the difficulty and novelty of the conception he is trying to illustrate by the terms in which he speaks of it ; it is twice over " this enigmatic notion " (TO arotrov rovro, cf. Tim. 49 A, ^akeirov real d/jivSpov etSo<? ... 51 B, /JLerakafji^dvov aTropcoTara TTTJ rov vorjrov teal SvcraXtarorarov of space). Necessary as the concep- tion of the " Instantaneous " is if we would think of change at all, it is indeed so strange and hard to grasp that the general tendency of thinking, even in modern times, has been to ignore it as far as possible. We have learned from natural science that behind every visible and apparently instantaneous change there lies a history of gradually ac- cumulating unseen inner modifications, and we have come to treat natura nil facit per saltum almost as a philoso- phical axiom ; it is not till we begin to take the task of analysing our own conceptions in earnest that we discover that the notion of an instantaneous transition, paradoxical as it is, cannot be dispensed with without making all change impossible -furca expellas, tamen usque recurrit. On the passage before us, in which this momentous conception makes its first appearance in philosophy, there is no need to linger. The argument proceeds straightforwardly enough as follows : The transition which we have seen it necessary to
