But the three subsections of this question may yield somewhat different answers. (i) Galen clearly distinguishes three levels of bodily analysis: qualities/elements; humours and homoeomerous or uniform parts; and organs. (Humours, such as blood or bile, are in a sense uniform, although in a more detailed distinction of levels, they may constitute a further layer, between elements and uniform parts, see Hipp. Elem. 8, 126–7.) Here, too, Galen is heavily indebted to Aristotle (in particular to book II of the Parts of Animals). A formulation which Galen uses in relation to this three-level analysis is that the organic parts arise from the “composition, amount, magnitude and shaping” of the uniform parts, which in turn depend on a correct balance of the elements hot, cold, wet and dry (San. Tu. I.1, 3). It seems clear, although it is not always explicitly stated, that analysis at the organic level should, in principle, involve the teleological cause; as we have seen, this may not always be the case of analysis at lower levels, though Galen is exercised by the problem of how biological substances or low-level organisms contain within them the principles which bring about the relevant teleological or functional aims (see further §6.2).