Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
The term epideictic seems to me however to imply display rather than demonstration, and to have a very different meaning from encomiastic. For although it includes laudatory oratory, it does not confine itself thereto.
Will any one deny the title of epideictic to panegyric? But yet panegyrics are advisory in form and frequently discuss the interests of Greece. We may therefore conclude that, while there are three kinds of oratory, all three devote themselves in part to the matter in land, and in part to display. But it may be that Romans are not
The second kind is deliberative, the third forensic oratory. All other species fall under these three genera: you will not find one in which we have not to praise or blame, to advise or dissuade, to drive home or refute a charge, while conciliation, narration, proof, exaggeration, extenuation and the moulding of the minds of the audience by exciting or allaying their passions, are common to all three kind of oratory.