Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
Some have preferred to give each of these points separate treatment, fearing that if they undertook them as a whole the burden would be greater than they
I. The commencement or exorditum as we call it in Latin is styled a proem by the Greeks. This seems to me a more appropriate name, because whereas we merely indicate that we are beginning our task, they clearly show that this portion is designed as an introduction to the subject on which the orator has to speak.
It may be because οἴμη means a tune, and players on the lyre have given the name of proem to the prelude which they perform to win the favour of the audience before entering upon the regular contest for the prize, that orators before beginning to plead make a few introductory remarks to win the indulgence of the judges.
Or it may be because οἶμος in Greek means a way, that the practice has arisen of calling an introduction a proem. But in any case there can be no doubt that by proem we mean the portion of a speech addressed to the judge before he has begun to consider the actual case. And it is a mistaken practice which we adopt in the schools of always assuming in our exordia that the judge is already acquainted with the case.