Within the depth-psychology and ancient philosophy corpus, orexis — the Greek term for desire or appetition in its broadest sense — occupies a pivotal position in debates about the structure of the soul, the causation of action, and the ethics of rational agency. Inwood’s sustained treatment in his 1985 study of early Stoicism establishes orexis as a technical genus covering both rational desire (boulêsis) and irrational appetite (epithumia), distinguishing it carefully from hormê (impulse) and orousis, while insisting that all forms of orexis are directed toward the apparent good. Nussbaum, in her 1986 analysis of Aristotelian psychology, foregrounds orexis as the irreducible unitary faculty of appetite — the orektikon — that Aristotle uses to criticize Platonic tripartition; for Nussbaum, orexis is always jointly necessary with cognition as an efficient cause of movement, and its intentional content is inseparable from its causal role. A further tension runs through the corpus: the Stoic project sought to reframe orexis within a rationalist framework by subordinating it to assent and logos, whereas Aristotle’s account grants it a degree of autonomy that makes human vulnerability to fortune ineliminable. The term thus serves as a node where theories of motivation, passions, ethical responsibility, and the good converge — making it indispensable for any serious engagement with ancient action theory in its psychological dimensions.