Defines rhetoric as a philosophy rather than an art, an unncessary tool. He's much more concerned with truth than Quintilian. Quintilian, on the other hand, points out that there are other methods of persuasion, such as money. The knowledge of speaking well. It helps if the speaker has knowledge of a broad range of subjects, and it is imperative that he knows the subject on which he speaks in-depth.
Arrangement depends of the speech depends on the occasion.