Attributed to Aristotle
«“We are what we repeatedly do. Excellence, then, is not an act, but a habit.”»
Misattributed
Verdict
It is not in Aristotle's work
Not Aristotle's: it is a paraphrase by Will Durant in The Story of Philosophy (1926), chapter on Aristotle, summarising in his own words the doctrine of Nicomachean Ethics II 1 on virtue as habit. The sentence circulates as if it were a direct quotation.
What they did say
Verified words of Aristotle
«“All men by nature desire to know.”»
Metafísica I (A) 1, 980a21. Inglés: trad. de W. D. Ross (Oxford, 1908); español: trad. propia del griego.
«“For it is owing to their wonder that men both now begin and at first began to philosophize.”»
Metafísica I (A) 2, 982b12–13. Inglés: trad. de W. D. Ross (1908); español: trad. propia.
«“And indeed the question which was raised of old and is raised now and always, and is always the subject of doubt, viz. what being is, is just the question, what is substance?”»
Metafísica VII (Z) 1, 1028b2–4. Inglés: trad. de W. D. Ross (1908); español: trad. propia.