For reasoning without passion has a direct tendency to justice, while if passion is infused, a contest and difference is excited between pleasure and pain on the one hand, and judgement and justice on the other.
 Plutarch, Moralia (c. 100 AD). copy citation

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Author Plutarch
Source Moralia
Topic judgement justice
Date c. 100 AD
Language English
Reference
Note Translated by Arthur Richard Shilleto
Weblink http://www.gutenberg.org/files/23639/23639-h/23639-h.htm

Context

“and in the councils of kings those who speak to ingratiate themselves do not favour either of the two cases, but give themselves up to passion without regard to what is expedient; and so those that rule in aristocracies do not allow orators to be pathetic in their pleadings. For reasoning without passion has a direct tendency to justice, while if passion is infused, a contest and difference is excited between pleasure and pain on the one hand, and judgement and justice on the other. For otherwise how is it that in philosophical speculations people are with little pain frequently induced by others to change their opinions, and even Aristotle himself and Democritus and Chrysippus have rejected without trouble or pain, and even with pleasure, some of the opinions which they formerly advocated?” source