A hormē, which I am translating by the term of art ‘impulse’, is not just an instinct or an underlying drive in an animal. This is worth insisting on at the outset, since the recognition of this is hard won and still not universally accepted.
Inwood establishes the foundational Stoic claim that impulse is a rational, volitional event and not a brute instinct or drive, correcting widespread scholarly misreading.
, Ethics and Human Action in Early Stoicism, 1985thesis