Aulus Gellius, Attic Nights, 11.11 The Difference Between Lying and Speaking an Untruth
11: The words of Publius Nigidius in which he has that there is a difference between lying [mentiri] and “speaking an untruth” [mendacium dicere]
These are the precise words of Publius Nigidius, a man of surpassing talents in the pursuit of the liberal arts, whom Marcus Cicero revered for his intelligence and his impressive control of his learning: “There is a difference between speaking an untruth and lying. A man who lies is not deceived himself; he is trying to deceive another. Someone who speaks an untruth, is himself deceived.”
He also adds this: “The man who lies, deceives as much as he can; but the one who speaks an untruth, does not deceive to the extent of his ability.” And then he adds as well on this matter: “A good man, ought to strain not to lie; a wise man should endeavor not to say anything untrue; the one affects the man himself, the other does not.” By Heracles, Nigidius so variously and cleverly sets out so many opinions on the same matter, as if he were saying something different each time!”
Verba P. Nigidii, quibus differre dicit “mentiri” et “mendacium dicere”.
Verba sunt ipsa haec P. Nigidii, hominis in studiis bonarum artium praecellentis, quem M. Cicero ingenii doctrinarumque nomine summe reveritus est: “Inter mendacium dicere et mentiri distat. Qui mentitur, ipse non fallitur, alterum fallere conatur; qui mendacium dicit, ipse fallitur”. II. Item hoc addidit: “Qui mentitur,” inquit “fallit, quantum in se est; at qui mendacium dicit, ipse non fallit, quantum in se est”. III. Item hoc quoque super eadem re dicit: “Vir bonus” inquit “praestare debet, ne mentiatur, prudens, ne mendacium dicat; alterum incidit in hominem, alterum non”. IV. Varie me hercule et lepide Nigidius tot sententias in eandem rem, quasi aliud atque aliud diceret, disparavit.