Institutio Oratoria

We should, however, remember that the orator must not follow the poets in everything, more especially in their freedom of language and their license in the use of figures. Poetry has been compared to the oratory of display, and further aims solely at giving pleasure, which it seeks to secure by inventing what is not merely untrue, but sometimes even incredible.

Further, we must bear in mind that it can be defended on the ground that it is tied by certain metrical necessities and consequently cannot always use straightforward and literal language, but is driven from the direct road to take refuge in certain by-ways of expression; and compelled not merely to change certain words, but to lengthen, contract, transpose or divide them, whereas the orator stands armed in the forefront of the battle, fights for a high stake and devotes all his effort to winning the victory.