All authorities unite in attributing to Aenesidemus the work of systematizing and presenting to the world the ten Tropes of [Greek:  epoche].  He was the first to conceive the project of opposing an organized philosophical system of Pyrrhonism to the dogmatism of his contemporaries.[1] Moreover, the fact that Diogenes introduces the Tropes into his life of Pyrrho, does not necessarily imply that he considered Pyrrho their author, for Diogenes invariably combines the teachings of the followers of a movement with those of the founders themselves; he gives these Tropes after speaking of Aenesidemus’ work entitled Pyrrhonean Hypotyposes, and apparently quotes from this book, in giving at least a part of his presentation of Pyrrhonism, either directly or through, the works of others.  Nietzsche proposes a correction of the text of Diogenes IX. 11, 79, which would make him quote the Tropes from a book by Theodosius,[2] author of a commentary on the works of Theodas.  No writer of antiquity claims for the Tropes an older source than the books of Aenesidemus, to whom Aristocles also attributes them.[3] They are not mentioned in Diogenes’ life of Timon, the immediate disciple of Pyrrho.  Cicero has no knowledge of them, and does not refer to them in his discussion of Scepticism.

    [1] Compare Saisset Op. cit. p. 78.

    [2] Brochard Op. cit. 254, Note 4.

    [3] Aristocles Eus. praep. ev. XIV. 18. 8.

Aenesidemus was undoubtedly the first to formulate these Tropes, but many things tend to show that they resulted, in reality, from the gradual classification of the results of the teachings of Pyrrho, in the subsequent development of thought from his own time to that of Aenesidemus.  The ideas contained in the Tropes were not original with Aenesidemus, but are more closely connected with the thought of earlier times.  The decidedly empirical character of the Tropes proves this connection, for the eight Tropes of Aetiology, which were original with Aenesidemus, bear a far stronger dialectic stamp, thus showing a more decided dialectic influence of the Academy than is found in the Tropes of [Greek:  epoche].  Many of the illustrations given of the Tropes also, testify to a time of greater antiquity than that of Aenesidemus.  The name Trope was well known in ancient times, and the number ten reminds us of the ten opposing principles of Pythagoras, and the ten categories of Aristotle, the fourth of which was the same as the eighth Trope.  The terminology, however, with very few exceptions, points to a later period than that of Pyrrho.  Zeller points out a number of expressions in both Diogenes’ and Sextus’ exposition of the Tropes, which could not date back farther than the time of Aenesidemus.[1] One of the most striking features of the whole presentation of the Tropes, especially as given by Sextus, is their mosaic character, stamping them not as the work of one person, but as a growth, and also an agglutinous growth, lacking very decidedly the symmetry of thought that the work of one mind would have shown.