 Speusippus’ successor as head of the Academy, Xenocrates, may actually have followed some version of the Pythagorean way of life, e.g., he was apparently a vegetarian, refused to give oaths, was protective of animals and followed a highly structured daily regimen, setting aside time for silence (Dillon 2003, 94–95 and 2014, 254–257; Burkert, however, argues that he rejected metempsychosis [1972a, 124]). He wrote a book entitled Things Pythagorean, the contents of which are unfortunately unknown (Diogenes Laertius IV 13). In the extant fragments of his writings, he refers to Pythagoras by name once, reporting that “he discovered that the musical intervals too did not arise apart from number” (Fr. 9 Heinze). Several doctrines of Xenocrates are also assigned to Pythagoras in the doxographical tradition, e.g., the definition of the soul as “a number moving itself,” which Xenocrates clearly developed on the basis of Plato’s Timaeus (Plutarch, On the Generation of the Soul 1012d; Aëtius IV 2.3–4). This suggests that Xenocrates, like Speusippus, may have assigned his own teachings back to Pythagoras or at least treated Pythagoras as his precursor in such as way that it was easy for others to do so (Burkert 1972a, 64–65; Dillon 2003, 153–154; Zhmud [2012a, 55 and 426–427] disputes this interpretation).