There is no great genius without a touch of madness.

[Nullum magnum ingenium sine mixtura dementiae fuit.]

Aristotle (384-322 BC) Greek philosopher

(Attributed)

Attributed to Aristotle in Seneca the Younger, "On Tranquility of Mind [De Tranquillitate Animi]" (17.10) (c. AD 60). (Source (Latin)).

Alternate translations:

• "There is no great genius without a mixture of madness." [Example (1851)]
• "No great genius was without a mixture of insanity." [tr. Langsdorf (1900)]
• "No great genius has ever been without a touch of insanity." [tr. Stewart (1900), "On Peace of Mind"]
• "No excellent soul is exempt from a mixture of madness." [Example (1906)]
• "No great genius has ever existed without some touch of madness." [tr. Basore (1932)]
• "No great genius has ever existed without a dash of lunacy." [tr. Davie (2007)]
• "There was never any great genius without a tincture of insanity." [tr. @sentantiq (2018)]
• "There was never a genius without a tincture of madness."
• "No great mind has ever existed without a touch of madness."

This quotation as such is not found in surviving Aristotle. It may either represent something from Aristotle that has been lost since Seneca, or else Seneca fabricating a quote, quoting something spurious, or paraphrasing something Aristotle did write, e.g., his comments about madness/melancholy and poets/prominent talents (here and here). See also the Pseudo-Aristotle, Problemata, Book 30, ch. 1:

Why is it that all those who have become eminent in philosophy or politics or poetry or the arts are clearly of an atrabilious temperament, and some of them to such an extent as to be affected by diseases caused by black bile, as is said to have happened to Heracles among the heroes? [tr. Forster (1927)]