Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
This class of figure may be employed under three conditions: first, if it is unsafe to speak openly; secondly, if it is unseemly to speak openly; and thirdly, when it is employed solely with a view to the elegance of what we say, and gives greater pleasure by reason of the novelty and variety thus introduced than if our meaning had been expressed in straightforward language.
The first of the three is of common occurrence in the schools, where we imagine conditions laid down by tyrants on abdication and decrees passed by the senate after a civil war, and it is a capital offence to accuse a person with what is past, what is not