Quintilian, Institutio Oratoria, Book 8
Harold Edgeworth Butler, Ed.

[29] I know that some may perhaps regard hyperbole as a species of amplification, since hyperbole can be [p. 281] employed to create an effect in either direction. But as the name is also applied to one of the tropes, I must postpone its consideration for the present. I would proceed to the immediate discussion of this subject but for the fact that others have given separate treatment to this form of artifice, [which employs words not in their literal, but in a metaphorical sense¹]. I shall therefore at this point indulge a desire now almost universal, and discuss a form of ornament which many regard as the chief, nay, almost the sole adornment of oratory.

V. When the ancients used the word sententia, they meant a feeling, or opinion. The word is frequently used in this sense by orators, and traces of this meaning are still found even in the speech of every day. For when we are going to take an oath we use the phrase ex animi nostri sententia (in accordance with what we hold is the solemn truth), and when we offer congratulations, we say that we do so ex sententia (with all our heart). The ancients, indeed, often expressed the same meaning by saying that they uttered their sensa; for they regarded senses as referring merely to the senses of the body.