Institutio Oratoria

But while exercise, which gives strength in all cases, is equally necessary both for orators and singing-masters, it is a different kind of exercise which they require. For the orator is too much occupied by civil affairs to be able to allot fixed times for taking a walk, and he cannot tune his voice through all the notes of the scale nor spare it exertion, since it is frequently necessary for him to speak in several cases in succession.

Nor is the same regime suitable as regards food: for the orator needs a strong and enduring voice rather than one which is soft and sweet, while the singer mellows all sounds, even the highest, by the modulation of his voice, whereas we have often to speak in harsh and agitated tones, must pass wakeful nights, swallow the soot that is produced by the midnight oil and stick to our work though our clothes be dripping with sweat.

Consequently, we must not attempt to mellow our voice by coddling it nor accustom it to the conditions which it would like to enjoy, but rather give it exercise suited to the tasks on which it will be employed, never allowing it to be impaired

The best method for securing such exercise is to learn passages by heart (for if we have to speak extempore, the passion inspired by our theme will distract us from all care for our voice), while the passages selected for the purpose should be as varied as possible, involving a combination of loud, argumentative, colloquial and modulated utterance, so that we may prepare ourselves for all exigencies simultaneously. This will be sufficient.