He gives an account himself of the work and of his design and plan in the following terms. (Epist. ad Att. xiii. 19.) “What I have lately written is in the manner of Aristotle, where the conversation is so managed that he himself has the principal part. I have finished the five books De Finibus Bonorum et Malorum, so as to give the Epicurean doctrine to Lucius Torquatus, the Stoic to Marcus Cato, and the Peripatetic to Marcus Cato. For I considered that their being dead would preclude all jealousy.” He does not, however, maintain the unity of scene or character throughout the five books. In the first book he relates a discussion which is represented as having taken place in his villa near Cumæ, in the presence of Caius Valerius Triarius, between himself and Lucius Manlius Torquatus, who is spoken of as being just about to enter his office as prætor, a circumstance which fixes the date of this imaginary discussion to B.C. 50, a time agreeing with the allusion (B. ii. 18,) to the great power of Pompey. In the first book he attacks the doctrines of the Epicurean school, and Torquatus defends them, alleging that they had been generally misunderstood; and in the second book Cicero enumerates the chief arguments with which the Stoics assailed them. In the third book the scene is laid in the library of Lucullus, where Cicero had accidentally met Cato; and from conversing on the books by which they were surrounded they proceeded to discuss the difference between the ethics of the Stoics, and those of the Old Academy and the Peripatetics; Cicero insisting that the disagreement was merely verbal and not real, and that Zeno was wrong in leaving Plato and Aristotle and establishing a new school; but Cato asserts, on the other hand, that the difference is a real one, and that the views held by the Stoics of the Supreme Good are of a much loftier and purer character than those which had been previously entertained. In the fourth book Cicero gives us the arguments with which the philosophers of the New Academy assailed the Stoics. And this conversation is supposed to have been held two years before that in the first book: for at the beginning of Book IV. there is a reference to the law for limiting the length of the speeches of counsel passed in the second consulship of Pompey, B.C. 55, as being only just passed.