SVF I.184

Original — Ancient Greek

τὴν δὲ εὐδαιμονίαν ὁ Ζήνων ὡρίσατο τὸν τρόπον τοῦτον· εὐδαιμονία δ᾽ ἐστὶν εὔροια βίου.

StoicOs Translation

Zeno defined happiness in this way: happiness is a good flow of life.

Context

Stobaeus (5th century CE) is here excerpting the systematic summary of Stoic ethics usually attributed to Arius Didymus — the same doxography that preserves Zeno's definition of the telos (SVF I.179). The definition is name-tagged as Zeno's; Sextus confirms it independently for the first three heads of the school.

Source notes:Text verified against H. von Arnim, SVF I (1903), no. 184, p. 46 (scanned page). Under the same number von Arnim prints the parallel Sextus, Adversus mathematicos XI 30, where the definition “happiness is a good flow of life” is attributed jointly to Zeno, Cleanthes and Chrysippus, with cross-references to Diogenes Laërtius 7.88 and Marcus Aurelius.

What the source actually tells us

A testimonium reporting Zeno's definition, with the two-word formula εὔροια βίου (euroia biou, “good flow of life”) very likely preserving Zeno's own coinage — it is short, striking, and attested across independent witnesses. The surrounding sentence is the doxographer's frame, not Zeno's text.

Philosophical meaning

Happiness as a good flow: not a possession, not a peak experience, but the smooth running of a life no longer dammed and broken by conflicting judgments and desires. The metaphor complements Zeno's definition of the goal as “living in agreement” (SVF I.179): where the soul's judgments cohere, life flows; where they fight, it churns. Marcus Aurelius still uses the image four and a half centuries later.

Practical wisdom

Ask of a day not “what did I get?” but “where did the flow break?” — the moment of friction is usually a judgment fighting another judgment. The Stoic aim is not to force events into smoothness (events are not up to us) but to remove the internal dams: contradictory demands, desires that outrun reason. Where those go, ease of flow follows.

Go deeper

• Read SVF I.179 — the end is to live in agreement →
• Study happiness and virtue in Stoic Ethics →