5. The introduction of Egyptian geometry into Hellas is universally ascribed to Thales, and it is extremely probable that he did visit Egypt; for he had a theory of the inundations of the Nile. In a well-known passage,[69] Herodotos gives three explanations of the fact that this alone of all rivers rises in summer and falls in winter; but, as his custom is in such cases, he does not name their authors. The first of them, however, that which attributes the floods to the Etesian winds, is ascribed to Thales in the _Placita_,[70] and also by many later writers. Now, those statements are derived from a treatise on the Rise of the Nile attributed to Aristotle and known to the Greek commentators, but now extant only in a Latin epitome of the thirteenth century.[71] In this work the first of the three theories mentioned by Herodotos is ascribed to Thales, the second to Euthymenes of Massalia, and the third to Anaxagoras. Where did Aristotle, or whoever wrote the book, get these names? We think naturally once more of Hekataios, whom Herodotos so often reproduces without mentioning his name; and this conjecture is much strengthened when we find that Hekataios actually mentioned Euthymenes.[72] We may conclude, then, that Thales really was in Egypt; and, perhaps, that Hekataios, in describing the Nile, took account, as was only natural, of his distinguished fellow-citizen’s views. Footnote 69: Herod. ii. 20. Footnote 70: Aet. iv. I. 1 (_Dox._ p. 384). Footnote 71: _Dox._ pp. 226-229. The Latin epitome will be found in Rose’s edition of the Aristotelian fragments. Footnote 72: Hekataios, fr. 278 (_F.H.G._ i. p. 19). [Sidenote: Thales and geometry.]