 This last criterion is more subjective than the first two and difficult cases arise. The fifth-century botanist Menestor (DK I 375) is discussed by Theophrastus and called one of “the old natural philosophers” (CP VI 3.5) with no mention of any Pythagoreanism. In this case, the inclusion of a Menestor in Iamblichus’ catalogue is not enough reason to regard Theophrastus’ Menestor as a Pythagorean. On the other hand, although Aristotle treats Hippasus separately from the Pythagoreans, as he does Archytas, the almost universal identification of Hippasus as a Pythagorean in the later tradition and his deep involvement in the biography of early Pythagoreanism, show that he should be regarded as a Pythagorean (on Hippasus, see section 3.4 below). The fifth-century figure Hippo (DK I 385), who is derided by Aristotle and paired with Thales as positing water as the first principle (Metaph. 984a3), is a particularly difficult case. An Hippo is listed in Iamblichus’ catalogue under Samos and Censorinus tells us that Aristoxenus assigned Hippo to Samos rather than Metapontum (DK I 385.4–5). This makes it look as if Aristoxenus may be responsible for including Hippo in the catalogue. Burkert has also tried to demonstrate connections between Hippo’s philosophy and that of the Pythagoreans (1972a, 290, n. 62). On the other hand, neither Aristotle nor Theophrastus nor any of the Aristotelian commentators call him a Pythagorean and the doxographers describe this Hippo as from Rhegium (e.g., Hippolytus in DK I 385.17). It is thus not clear whether we are dealing with one person or two people named Hippo and it is doubtful that the Hippo discussed by the Peripatetics was a Pythagorean (Zhmud regards Hippo as well as Menestor and Theodorus as Pythagoreans — 2012a, 126–128). Those figures of the sixth, fifth and fourth century who have the best claim to be considered Pythagoreans will be discussed in the following sections.