Theophrastos tells us that Empedokles made no distinction between thought and perception, a remark already made by Aristotle.[644] The chief seat of perception was the blood, in which the four elements are most evenly mixed, and especially the blood near the heart (fr. 105).[645] This does not, however, exclude the idea that other parts of the body may perceive also; indeed, Empedokles held that all things have their share of thought (fr. 103). But the blood was specially sensitive because of its finer mixture.[646] From this it naturally follows that Empedokles adopted the view, already maintained in the Second Part of the poem of Parmenides (fr. 16), that our knowledge varies with the varying constitution of our bodies (fr. 106). This consideration became very important later on as one of the foundations of scepticism; but Empedokles himself only drew from it the conclusion that we must make the best use we can of our senses, and check one by the other (fr. 4). Footnote 644: Arist. _de An._ Γ, 3. 427 a 21. Footnote 645: R. P. 178 a. This was the characteristic doctrine of the Sicilian school, from whom it passed to Aristotle and the Stoics. Plato and Hippokrates, on the other hand, adopted the view of Alkmaion (§ 97) that the brain was the seat of consciousness. Kritias (Arist. _de An._ Α, 2. 405 b 6) probably got the Sicilian doctrine from Gorgias. At a later date, Philistion of Syracuse, Plato’s friend, substituted the ψυχικὸν πνεῦμα (“animal spirits”) which circulated along with the blood. Footnote 646: Beare, p. 253. [Sidenote: Theology and religion.] 119. The theoretical theology of Empedokles reminds us of Xenophanes, his practical religious teaching of Pythagoras and the Orphics. We are told in the earlier part of the poem that certain “gods” are composed of the elements; and that therefore though they “live long lives” they must pass away (fr. 21). We have seen that the elements and the Sphere are also called gods, but that is in quite another sense of the word.