Here a period of seven or eight years intervenes, during which he composed little of importance besides his Orations. He then published the _De claris Oratoribus_ and _Orator_; and a year later, when he was sixty-three, his _Academicae Quaestiones_, in the retirement from public business to which he was driven by the dictatorship of Caesar. This work had originally consisted of two dialogues, which he entitled _Catulus_ and _Lucullus_, from the names of the respective speakers in each. These he now remodelled and enlarged into four books, dedicating them to Varro, whom he introduced as advocating, in the presence of Atticus, the tenets of Antiochus, while he himself defended those of Philo. Of this most valuable composition, only the second book (_Lucullus_) of the first edition and part of the first book of the second are now extant. In the former of those two, Lucullus argues against, and Cicero for, the Academic sect, in the presence of Catulus and Hortensius; in the latter, Varro pursues the history of philosophy from Socrates to Arcesilas, and Cicero continues it down to the time of Carneades. In the second edition the style was corrected, the matter condensed, and the whole polished with extraordinary care and diligence.[219] The same year he published his treatise _De Finibus_, or "On the chief good," in five books, in which are explained the sentiments of the Epicureans, Stoics, and Peripatetics on the subject. This is the earliest of his works in which the dialogue is of a disputatious character. It is opened with a defence of the Epicurean tenets, concerning pleasure, by Torquatus; to which Cicero replies at length. The scene then shifts from the Cuman villa to the library of young Lucullus (his father being dead), where the Stoic Cato expatiates on the sublimity of the system which maintains the existence of one only good, and is answered by Cicero in the character of a Peripatetic. Lastly, Piso, in a conversation held at Athens, enters into an explanation of the doctrine of Aristotle, that happiness is the greatest good. The general style of this treatise is elegant and perspicuous; and the last book in particular has great variety and splendour of diction.