The three styles of speaking[91] arise from the orator’s three objects: (69) to prove, to please, to move. Aptness, then, demands adjustment not only to the speaker (71) and the audience (72), but also to the object. What is proper to the plain style (_genus tenue_, 75)? This sounds so ordinary that it seems easier than it is; for, though not strong, it must be sound. It is untrammeled by cadences (77), is free without rambling, and neither fits word to word nor avoids the pleasant negligence of one elaborating matter rather than manner. It avoids periodic structure (85) and dramatic delivery (86); but admits a careful use of wit (87-90). The median style (_genus medium_, 92), adjusted to the winning of sympathy (_conciliare_), aimed at the ἦθος of the audience, has as its chief character _suavitas_; as its chief exponent, Demetrius of Phalerum. The high style (_genus grande_, 97), aiming at πάθος, though it is the acme, is not to be pursued exclusively; for the perfect orator must be master of all three (100); the three may be modified (103), combined, and varied; and variety is necessary (109) both in any given speech and as a habit. After a summary, 113-139, of the orator’s necessary knowledge, especially of the other parts of rhetoric, Cicero passes to his main topic, harmony. Explaining (140-148) the importance of this, he defines it in its simplest aspect of euphony (149); negatively as the avoidance of hiatus, stops, and other awkward combinations, positively as balance, symmetry, the rounding out of the phrase by correspondence (165).