The stone: up and down are indifferent. The image of a thrown stone: rising and falling (ἀνενεχθῆναι/κατενεχθῆναι) are to it neither TERMgood nor TERMevil, but simply its natural motion. So too the external turns (success/failure, life/death) are indifferent in themselves: value lies not in what is undergone but in action (cf. 9.16). A parallel to the image of the ball at 8.20: the descent is no evil to the thing, but a planned and equal phase.

The argument from the converse. If the stone's rising is not its "good," then its falling is not its "evil": both lie outside its ἀρετή. Apply it to yourself, and the fear of "falling" (illness, disgrace, death) loses its footing. The governing discipline is desire (evenness toward the indifferent).