His treatise _De claris Oratoribus_ was written after an interval of nine years, about the time of Cato's death, when he was sixty-one, and is thrown into the shape of a dialogue between Brutus, Atticus, and himself. He begins with Solon, and after briefly mentioning the orators of Greece, proceeds to those of his own country, so as to take in the whole period from the time of Junius Brutus down to himself. About the same time he wrote his _Orator_; in which he directs his attention principally to diction and delivery, as in his _De Inventione_ and _Topica_ he considers the matter of an oration.[211] This treatise is of a less practical nature than the rest.[212] It adopts the principles of Plato, and delineates the perfect orator according to the abstract conceptions of the intellect rather than the deductions of observation and experience. Hence he sets out with a definition of the perfectly eloquent man, whose characteristic it is to express himself with propriety on all subjects, whether humble, great, or of an intermediate character;[213] and here he has an opportunity of paying some indirect compliments to himself. With this work he was so well satisfied that he does not scruple to declare, in a letter to a friend, that he was ready to rest on its merits his reputation for judgment in Oratory.[214] The treatise _De partitione Oratoria_, or on the three parts of rhetoric, is a kind of catechism between Cicero and his son, drawn up for the use of the latter at the same time with the two preceding. It is the most systematic and perspicuous of his rhetorical works, but seems to be but the rough draught of what he originally intended.[215] 10. The connection which we have been able to preserve between the rhetorical writings of Cicero cannot be attained in his moral, political, and metaphysical treatises; partly from the extent of the subject, partly from the losses occasioned by time, partly from the inconsistency which we have warned the reader to expect in his sentiments. In our enumeration, therefore, we shall observe no other order than that which the date of their composition furnishes.