Quintilian on the Five Divisions of Oratory

Inst. Orat. III.1-3 (LCL, Butler)

1. The whole art of oratory, as the most and greatest writers have taught, consists of five parts: invention, arrangement, expression, memory, and delivery or action (the last is designated by either of these terms). But every speech, by which any purpose is expressed, must of necessity consist of both matter and words; 2. and, if it is short and included in one sentence, it may perhaps call for no further consideration. But a speech of greater length requires attention to a greater number of particulars, for it is not only of consequence what we say and how we say it, but also where we say it; there is need therefore also for arrangement. But we cannot say everything that our subject demands, nor everything in its proper place, without the assistance of memory, which will accordingly constitute a fourth part. 3. And a delivery which is unbecoming either as to voice or gesture, vitiates and almost renders ineffectual all those other requisites of eloquence. To delivery therefore must necessarily be assigned the fifth place.