Genre and place in the book. A terse maxim of contrast: the physical motion of the elements against the motion of virtue. The principal discipline is desire (the exaltation of virtue as the divine good above the physical order). It continues the theme of the right "motion" (κίνησις) from 06-16 (the valuable thing is to move according to one's own constitution).

The motions of the elements (φοραὶ τῶν στοιχείων). "Up, down, in a circle" — the natural motions of the four TERMelements: earth and water tend downward, fire and air upward, the heavenly (aether) in a circle. This is the domain of physical necessity, the rectilinear and circular mechanics of the cosmos.

The motion of virtue (ἡ τῆς ἀρετῆς κίνησις). The motion of TERMvirtue is "in none of these": it is "something more divine" (θειότερόν τι), advancing "by a way hard to trace" (ὁδῷ δυσεπινοήτῳ), and it "fares well on its road" (εὐοδεῖ). Moral motion is not measured by physical trajectories: it is on another, higher plane. The verb εὐοδεῖ ("has a good road") echoes εὔροια βίου — the "smooth flow of life," the Stoic image of happiness: virtue moves, and its road runs well.

Disciplines and parallels. The principal one is desire (virtue as the highest, divine good, above the physical). Parallels: 06-16 (the right κίνησις — activity according to one's own constitution); the motions of the elements — Stoic physics of the elements (SVF II 413 ff.); εὐοδεῖ ↔ εὔροια (the smooth flow of life); the "way hard to trace" — moral progress (προκοπή) is inconspicuous, not like physical mechanics.