Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
Every speech however consists at once of that which is expressed and that which expresses, that is to say of matter and words. Skill in speaking is perfected by nature, art and practice, to which some add a fourth department, namely imitation, which I however prefer to include under art.
There are also three aims which the orator must always have in view; he must instruct, move and charm his hearers. This is a clearer division than that made by those who divide the task of oratory into that which relates to things and that which concerns the emotions,