  Aristotle asserted that only humans had rational souls, while the locomotive souls shared by all animals, human and nonhuman, endowed animals with instincts suited to their successful reproduction and survival. Sorabji (1993) argues that the denial of reason to animals created a crisis for Greek thought, requiring a “wholesale reanalysis” (p. 7) of the nature of mental capacities, and a revision in thinking about “man and his place in nature above the animals” (ibid.). The argument about what is reasoning, and whether animals display it, remains with us 25 centuries later, as evidenced by the volume Rational Animals? (Hurley &amp; Nudds 2006). The Great Chain of Being derived from early Christian interpretation of Aristotle's scale of nature (Lovejoy 1936) provides another Aristotelian influence on the debate about animal minds.