6. The treatise _De Finibus Bonorum et Malorum_ discusses various theories of the _summum bonum_--the Epicurean in Books i.-ii., the Stoic in iii.-iv., the Peripatetic in v. The scene of the dialogue changes from Cumae to Tusculum and then to the Academy at Athens. The work was dedicated to Brutus in June, 45 (_ad Att._ xiii. 12, 3).
7. The _Academics_ appeared in two editions. Of the original edition Book ii., entitled _Lucullus_, has survived; the speakers in it are Lucullus, Catulus, Hortensius, and Cicero, and the scene, Hortensius' villa. Cicero was not satisfied with this arrangement (_ad Att._ xiii. 12, 3, 'homines nobiles illi quidem, sed nullo modo philologi, nimis acute locuntur'), and after provisionally transferring the parts of Lucullus, Catulus, and Hortensius, to Cato and Brutus, he finally adopted the suggestion of Atticus to gratify Varro by giving him a share in the dialogue together with Atticus and himself (_ad Att._ xiii. 13, 1, 'commotus tuis litteris, quod ad me de Varrone scripseras, totam Academiam ab hominibus nobilissimis abstuli transtulique ad nostrum sodalem et ex duobus libris contuli in quattuor'). Of this second edition in four Books we possess only Book i. (incomplete), and fragments of the others; the scene is at Cumae. The dedicatory epistle to Varro is still preserved (_ad Fam._ ix. 8).
8. In the five Books of _Tusculanae Disputationes_, conversations between Cicero and a friend at his Tusculan villa, the subject is the chief essentials for happiness. Book i. inculcates the proper attitude towards death, ii. to grief, iii. to pain, iv. to other trials, v. asserts the sufficiency of virtue for happiness. The treatise is dedicated to Brutus, and was finished by B.C. 44, in which year (_ad Att._ xv. 2, 4) the first Book is known to Atticus.
9. _De Natura Deorum_, in three Books, is also addressed to Brutus. The Epicurean, Stoic, and Peripatetic doctrines are represented by C. Velleius, Q. Lucilius Balbus, and C. Aurelius Cotta, respectively. This treatise was written after the _Tusculans_ (_de Div._ ii. 3): in July 45 (_ad Att._ xiii. 39, 2) Atticus is asked for the loan of Φαίδρου περὶ θεῶν and περὶ Παλλάδος.
10. The essay _De Senectute_, called also _Cato Maior_ after the principal speaker in the dialogue, was addressed to Atticus at the end of 45 or early in 44 (_de Div._ ii. 3; _ad Att._ xiv. 21, 3).