For if any one proceeds in a passion to inflict punishment, he will never observe that happy mean which lies between excess and defect.
 Marcus Tullius Cicero, On Duties (44 BC). copy citation

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Author Marcus Tullius Cicero
Source On Duties
Topic punishment passion
Date 44 BC
Language English
Reference
Note Translated by Walter Miller
Weblink http://www.constitution.org/rom/de_officiis.htm

Context

“{89} We should take care also that the punishment shall not be out of proportion to the offence, and that some shall not be chastised for the same fault for which others are not even called to account. In administering punishment it is above all necessary to allow no trace of anger. For if any one proceeds in a passion to inflict punishment, he will never observe that happy mean which lies between excess and defect. This doctrine of the mean is approved by the Peripatetics and wisely approved, if only they did not speak in praise of anger and tell us that it is a gift bestowed on us by Nature for a good purpose.” source