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 in it the order was that of the successive schools, and short historical and chronological notices were inserted.
Doxographers.
8. A work of this kind was, of course, a godsend to the epitomators and compilers of handbooks, who flourished more and more as the Greek genius declined. These either followed Theophrastos in arranging the subject-matter under heads, or else they broke up his work, and rearranged his statements under the names of the various philosophers to whom they applied. This latter class form the natural transition between the doxographers proper and the biographers, so I have ventured to distinguish them by the name of biographical doxographers.
I. Doxographers Proper
The Placita and Stobaios.
9. These are now represented by two works, viz. the Placita Philosophorum, included among the writings ascribed to Plutarch, and the Eclogae Physicae of John Stobaios (c. 470 A.D.). The latter originally formed one work with the Florilegium of the same author, and includes a transcript of some epitome substantially identical with the pseudo-Plutarchean Placita. It is, however, demonstrable that neither the Placita nor the doxography of the Eclogae is the original of the other. The latter is usually the fuller of the two, and yet the former must be earlier; for it was used by Athenagoras for his defence of the Christians in 177 A.D. (Dox. p. 4). It was also the source of the notices in Eusebios and Cyril, and of the History of Philosophy ascribed to Galen. From these writers many important corrections of the text have been derived (Dox. pp. 5 sqq.).
Another writer who made use of the Placita is Achilles (not Achilles Tatius). Extracts from his Εἰσαγωγή to the Phaenomena of Aratos are included in the Uranologion of Petavius, pp. 121-164. His date is uncertain, but probably he belongs to the third century A.D. (Dox. p. 18).
Aetios.
10. What, then, was the common source of the Placita and the Eclogae? Diels has shown that Theodoret (c. 445 A.D.) had access to it; for in some cases he gives a fuller form of statements made in these two works. Not only so, but he also names that source; for he refers us (Gr. aff. cur. iv. 31) to Ἀετίου τὴν περὶ ἀρεσκόντων συναγωγήν. Diels has accordingly printed the Placita in parallel columns with the relevant parts of the Eclogae, under the title of Aetii Placita. The quotations from “Plutarch” by later writers, and the extracts of Theodoret from Aetios, are also given at the foot of each page.