Plutarch Praecepta gerendae reipublicae 9

[9] And the statesman must bring to the struggle of statecraft - a struggle which is not unimportant, but calls for all one’s fighting power - speech which is severely trained in firmness of voice and strength of lungs, that he may not be frequently so weary and burnt out as to be defeated by some Cato, when he had no hope of winning his cause by persuasion because the popular assembly or the senate was gained over beforehand by favours and interests, used to get up and speak the whole day, thus destroying his opponents’ opportunity. On the subject, then, of the preparation of one’s speech and the way to use it these remarks are enough for one who has the ability to go on and discover the conclusions to be drawn from them.

[9] It is requisite also for the champion of the commonweal to bring to this not slight but all-concerning contest a firm and solid speech, attended with a strong habit of voice and a long lasting breath, lest, being tired and spent with speaking, he chance to be overcome by Cato, when he had no hopes of persuading the people or senate, whom he found prepossessed by the courtships and endeavors of the contrary party, was wont to rise up and hold them a whole day with an oration, by that means depriving his adversaries of their opportunity. And thus much concerning the preparation and use of speech may be sufficient for him who can of himself find out and add What necessarily follows from it.