 As already noted, this heading comes under ‘logic’ in Sextus Empiricus. No one reports anything for Xenocrates about what we would think of as pure logic; Sextus (Adversus mathematicos vii 147–149) gives us a scrap about epistemology. Xenocrates is supposed to have divided the substances or entities into three groups: perceptible, intelligible, and believable (also referred to as ‘composite’ and ‘mixed’). The intelligible ones were objects of knowledge, which Xenocrates apparently spoke of as ‘epistemonic logos’ or ‘knowing account’, and were ‘located’ outside the heavens. The perceptible ones were objects of perception, which was capable of attaining truth about them but nothing that counted as knowledge; they were within the heavens. The composite ones were the heavenly objects themselves, and objects of belief, which is sometimes true and sometimes false.