Full Idea
Chrysippus considered destiny to be not a cause sufficient of itself but only a predisposing cause.
Gist of Idea
Destiny is only a predisposing cause, not a sufficient cause
Source
report of Chrysippus (fragments/reports [c.240 BCE], fr 997) by Plutarch - 70: Stoic Self-contradictions 1056b
Book Reference
Plutarch: 'Moralia - vol 13 part 2', ed/tr. Cherniss,Harold [Harvard Loeb 1993], p.595
A Reaction
This appears to be a rejection of determinism, and is the equivalent of Epicurus' introduction of the 'swerve' in atoms. They had suddenly become bothered about the free will problem in about 305 BCE. There must be other non-destiny causes?