It is important to consider the historically specific attitude to authority—to “the ancients”—that is in play here. As we have seen, Galen apparently regards certain propositions as evident to reason which we might rather think are “endoxic”, or indeed simply well established in traditional thought. More specifically, Galen has an enormous explicit admiration for certain authors already regarded as classical in his time, most especially Hippocrates and Plato, and devotes lengthy texts to their exegesis. He is both influenced by previous authors and exercised to present his own views as consistent with a body of traditional thought. But his latter process is not a straightforward or uncritical one: different sets of authors are lined up as authority in different contexts; and authors highly respected in certain contexts become the object of fierce criticism in others. (On these issues see Lloyd 1988, 1993; Singer 1996, 2013, Ch. 4, 2021a; Vegetti 1999; von Staden 2009.) Galen explicitly states that he does not rely on Hippocrates, “as others do”, uncritically or reverentially, but rather quotes him because he sees “that his demonstrations are secure” (QAM 9, 399–400). So, too, with Plato: although agreeing with much of Platonic doctrine as he understands it, and in a sense appearing to present himself “tribally” as a Platonist, Galen is quite capable of disagreeing with Plato on points of detail.