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.