more than any one else that we owe the preservation of the fragments. He had, of course, the library of the Academy at his disposal, at any rate up to A.D. 529.
B.—DOXOGRAPHERS
6.The Doxographi Graeci. The Doxographi Graeci of Professor Hermann Diels (1879) threw an entirely new light upon the filiation of the later sources; and we can only estimate justly the value of statements derived from these if we bear constantly in mind the results of his investigation. Here it will only be possible to give an outline which may help the reader to find his way in the Doxographi Graeci itself.
7.The "Opinions" of Theophrastos. By the term doxographers we understand all those writers who relate the opinions of the Greek philosophers, and who derive their material, directly or indirectly, from the great work of Theophrastos, (Φυσικῶν δοξῶν ιή (Diog. v. 46). Of this work, one considerable chapter, that entitled Περὶ αἰσθήσεων, has been preserved (Dox. pp. 499-527). And Usener, following Brandis, further showed that there were important fragments of it contained in the commentary of Simplicius (sixth cent. A.D.) on the First Book of Aristotle's Φυσικὴ ἀκρόασις (Usener, Analecta Theophrastea, pp. 25 sqq.). These extracts Simplicius seems to have borrowed in turn from Alexander of Aphrodisias (c. A.D. 200); cf. Dox. p. 112 sqq. We thus possess a very considerable portion of the First Book, which dealt with the ἀρχαί, as well as practically the whole of the last Book.
From these remains it clearly appears that the method of Theophrastos was to discuss in separate books the leading topics which had engaged the attention of philosophers from Thales to Plato. The chronological order was not observed; the philosophers were grouped according to the affinity of their doctrine, the differences between those who appeared to agree most closely being carefully noted. The First Book, however, was in some degree exceptional; for
