SVF I.68

Original — Ancient Greek

εἶναι τὴν ἐπιστήμην κατάληψιν ἀσφαλῆ καὶ ἀμετάπτωτον ὑπὸ λόγου. — τὴν ἄγνοιαν μεταπτωτικὴν εἶναι συγκατάθεσιν καὶ ἀσθενῆ. — ἐπιστήμην εἶναι τὴν ἀσφαλῆ καὶ βεβαίαν καὶ ἀμετάθετον ὑπὸ λόγου κατάληψιν. — αὐτήν τε τὴν ἐπιστήμην φασὶν ἢ κατάληψιν ἀσφαλῆ, ἢ ἕξιν ἐν φαντασιῶν προσδέξει ἀμετάπτωτον ὑπὸ λόγου.

StoicOs Translation

Knowledge is a grasp that is secure and cannot be overturned by argument. — Ignorance is assent that is changeable and weak. — Knowledge is the grasp that is secure, firm and unalterable by argument. — And knowledge itself, they say, is either a secure grasp or a disposition in the reception of impressions that cannot be overturned by argument.

Context

Von Arnim assembles here the Greek school-definitions of knowledge and its opposite: two from Stobaeus' anthology (drawing on the ethical doxography of Arius Didymus), one from Sextus Empiricus, one from Diogenes Laërtius. Together with the Latin of Cicero (SVF I.60) they show how the definition circulated across the whole ancient tradition.

Source notes:Greek text verified against H. von Arnim, SVF I (1903), no. 68, p. 20 (scanned page). Von Arnim joins four witnesses with dashes: Stobaeus Ecl. II 73,19 W. (definition of epistēmē); ib. II 111,20 (definition of agnoia); Sextus Empiricus, adv. math. 7.151; Diogenes Laërtius 7.47 — multiply attested, though partly from a shared school tradition. The parallel Latin slice (Cicero, Acad. post. 1.41: scientiam/inscientiam) is presented in full context under SVF I.60.

What the source actually tells us

These are doxographic testimonia: none quotes a named book of Zeno, and the definitions are given as Stoic school doctrine that Cicero's parallel account traces back to Zeno personally. The four Greek formulations differ slightly (“cannot be overturned” ἀμετάπτωτος vs. “unalterable” ἀμετάθετος; “grasp” vs. “disposition in the reception of impressions”) — the differences are preserved, not smoothed over.

Philosophical meaning

The Stoic definition of knowledge sets a hard standard: a grasp so secure that no argument can dislodge it. Its opposite is not mere absence of information but weak, changeable assent — saying yes too easily. Knowledge, on this view, is a stability of the mind: the same grasp, tested and immovable.

Scholarly uncertainty

Whether these exact Greek formulations are Zeno's own or the school's later standardisation cannot be decided; the attribution to Zeno rests on the parallel in Cicero (SVF I.60). The witnesses may draw on a shared doxographic tradition rather than reading Zeno independently.

Go deeper

• Read SVF I.60 — Cicero's full account of Zeno's epistemology →
• Read SVF I.69 — the grasp between knowledge and opinion →