The Material and Sources Plato's Dream of M. F. BURNYEAT y quarrel is with a certain, near-orthodox approach to the section of Plato's Theaetetus c an `/1 Dream (201 ff.), approach typified by Runciman's remark: "That the 'dream' did in fact derive from some other philosopher or school seems virtually certain from the language in which it is introduced and from the occurrence of the word En?aT-??ra5which is nowhere used by Plato except here."' In attempting to show that this claim is ill-founded I shall for the most part be concerned with matters peripheral to the interpretation of the Dream itself, but the discussion may be useful as a prolegomenon to an interpretation which locates the Dream section firmly within Plato's own philosophic concerns instead of seeking to account for it wholly or partly in terms of alien sources. The immediate stimulus f or the Dyeam Socrates' conclusion at 201 c that knowledge and true belief are not the same reminds Theaetetus that he heard someone making that very point. More precisely, this someone maintained (a) that knowledge was true belief conjoined with a logos, (b) that there could be knowl- edge of a thing if and only if it had a logos.2 Now it is clear from proposition (b) that the logos which turns true belief into knowledge is a logos of the thing known. Thus understood, (a) has as a direct consequence the unknowability of anything of which a logos cannot be given. But in the sequel Socrates insists on keeping (a), the definition as such, separate from the distinction between knowables and unknowables introduced by (b) (cf. 202 cd, 101 206 c). He can do this because in the Greek (b) is stated in such a manner as to imply something which is not a consequence of (a): that there actually are Logos-lacking unknowables. This is the feature on which Socrates now fastens. He opens with a fairly emphatic compliment for Theaetetus (201 d 4: xocac?S the first of several expressions of high regard for this, the dialogue's third definition of knowledge (202 d, 208 b, 209 e; at 203 de (b) too is honoured, though here comparison with 202 d 10 may suggest a trace of irony). He then inquires for the criteria by which knowable and unknowable were distinguished in the position as it was expounded to Theaetetus, in case it was made on the same basis as he too has heard it made. That is, Socrates recognises the distinction as one he has encountered before, without, however, suggesting that this is because it is the intellectual property of some particular source with which he too is acquainted. On the contrary, when Theaetetus doubts he can discover3 the basis for the distinction between knowable and unknowable, though he thinks he could follow4 someone else's elucidation of it, Socrates comes to his rescue by recounting the way he has heard the distinction drawn, not by Theaetetus' source, but by a plurality of unidentified expositors. Thus the Dream is introduced to supplement or to clarify the position sketched by Theaetetus, rather than to refresh his memory of a particular exposition of it. It goes back over the whole of the ground covered by (a) and (b), concentrating on the point most in need of clarification, the distinction between knowable and unknow- able. That is the motive for introducing a dream in place of Theaetetus' dream, or to match or compare with it (201 d 8: &xovE 6vap «vTi What Socrates says here is nothing more complicated than 102 .