[Sidenote: The fourth period.] The last period was for the most part a time of quiet literary work for Cicero. Only after Cæsar’s death did he return to public life. In 46 B. C. he thanked Cæsar, in the oration _For Marcellus_, for allowing Marcellus, who had been consul in 51 B. C., to return to Rome; later in the same year he pleaded the case of Quintus Ligarius in the speech _For Ligarius_, and in 45 B. C. he spoke in behalf of Deiotarus, tetrarch of Galicia, who had been accused of treachery to Cæsar (_For King Deiotarus_), but these are the only speeches of this period except the fourteen _Philippics_, directed against Antony, all of which belong to the short time between the second of September, 44 B. C., and the twenty-second of April, 43 B. C. In these Cicero shows his old energy and fire, but not quite his earlier power. The name _Philippics_ was given to these speeches almost from the very first, and was in fact authorized by Cicero himself, who welcomed the parallel between himself, arousing and encouraging the Romans against Antony, and Demosthenes urging the Athenians to oppose Philip. But these orations were the work of a few months; by far the greater part of the years after 50 B. C. was occupied with other things. [Sidenote: Rhetorical and philosophical works.] In the three years 46-44 B. C. appeared the rhetorical writings _Brutus_, the _Orator_, the _Divisions of Oratory_, the essay _On the Best Kind of Orators_, and the long series of philosophical dialogues and treatises, the most important of which are the _De Finibus Bonorum et Malorum_, a discussion of the different theories respecting the highest good, in five books; the _Academics_, two books of which are preserved; the _Tusculan Disputations_, in five books, treating of the chief essentials for happiness; the treatise _On the Nature of the Gods_, in three books; and the three books _On Duties_ (_De Officiis_); to which should be added, on account of their beauty of style and sentiment, the _Cato Maior_ (_On Old Age_) and the _Lælius_ (_On Friendship_). Cicero’s extant works comprise fifty-seven orations and fragments of twenty more, seven rhetorical treatises, thirteen philosophical treatises, including those _On the State_ and _On Laws_, and about eight hundred and sixty letters, among which are ninety addressed to him by his correspondents. Among the lost works are a few historical writings and several translations from the Greek.