SVF I.93

Original — Ancient Greek

Ζήνων ἔφησε χρόνον εἶναι κινήσεως διάστημα, τοῦτο δὲ καὶ μέτρον καὶ κριτήριον τάχους τε καὶ βραδύτητος ὅπως ἔχει ⟨ἕκαστα⟩. κατὰ τοῦτον δὲ γίγνεσθαι τὰ γινόμενα καὶ τὰ περαινόμενα ἅπαντα καὶ τὰ ὄντα εἶναι.

StoicOs Translation

Zeno said that time is the interval of motion, and that it is also the measure and criterion of quickness and slowness, of how ⟨each thing⟩ stands. And in accordance with it everything that comes to be and is brought to completion comes about, and the things that are, are.

Context

The passage survives in Stobaeus' Anthology (5th century CE), which here excerpts the physical doxography of Arius Didymus (1st century BCE). Von Arnim adds a second, later witness — the Aristotle-commentator Simplicius (6th century CE) — who transmits a slightly fuller formula: time as the interval “of all motion without qualification”.

Source notes:Greek text verified against H. von Arnim, SVF I (1903), no. 93, p. 26 (scanned page). The word ⟨ἕκαστα⟩ in angle brackets is an editorial supplement as printed by von Arnim. Under the same number von Arnim adds a second witness: Simplicius, in Cat. 80a4 — „τῶν δὲ Στωικῶν Ζήνων μὲν πάσης ἁπλῶς κινήσεως διάστημα τὸν χρόνον εἶναι“. The Stobaeus passage reaches us through the epitome of Arius Didymus.

What the source actually tells us

This is a doxographic testimonium: the report “Zeno said” (Ζήνων ἔφησε) attributes the definition explicitly, but the sentence is the doxographer's summary, not a quotation from a named book of Zeno. The supplement ⟨ἕκαστα⟩ is a modern editorial addition, printed in angle brackets, and no part of the transmitted text. The core definition — time as the interval of motion — is confirmed in slightly different wording by Simplicius.

Philosophical meaning

This is the earliest Stoic definition of time. Time is not an independent container in which things happen: it is the dimension of motion itself — the interval that motion opens up — and thereby the measure by which fast and slow, before and after, can be judged at all. Later Stoics refined the formula (Chrysippus: the interval of the motion of the cosmos), but the physical, motion-bound conception of time begins here with Zeno.

Scholarly uncertainty

The two witnesses give the formula with different scope: Stobaeus/Arius Didymus simply “interval of motion”, Simplicius “interval of all motion without qualification” — the latter perhaps sharpening the definition against Chrysippus' cosmic version. Where exactly Zeno's own wording ends and the doxographers' compression begins cannot be determined.

Go deeper

• Study time and the cosmos in Stoic Physics →
• What is the Inner Citadel? →