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