Finibus_, is taken from the best writings of the different philosophers whose doctrines he explains. The first book closely follows the tract of Epicurus, Κυριων δοξων. Cicero’s second book, in which he refutes Epicurism, is borrowed from the stoic Chrysippus, who wrote ten books Of the beautiful, and of pleasure, (Περι τοῦ καλοῦ και της ἡδονης,) wherein he canvassed the Epicurean tenets concerning the Supreme Good and Evil. His third book is derived from a treatise of the same Chrysippus, entitled Περι τελων(415). The fourth, where he refutes the Stoics, is from the writings of Polemo, who, following the example of his master Xenocrates, amended the Academic doctrines, and nearly accommodated them on this subject of Good and Evil to the opinions of the ancient Peripatetics. Some works of Antiochus of Ascalon, who, in the time of Cicero, was the head of the old Academy, supplied the materials for the concluding dialogue. The work _De Finibus_ was written in 708, and though begun subsequently to the _Academica_, was finished before it. The period, however, of the three different conferences of which it consists, is laid a considerable time before the date of its publication. It is evident that the first dialogue is supposed to be held in 703, since Torquatus, the principal speaker, who perished in the civil war, is mentioned as _Prætor Designatus_, and this prætorship he bore in the year 704. The following conference is placed subsequently, at least, to the death of the great Lucullus, who died in 701. The last dialogue is carried more than thirty years back, being laid in 674, when Cicero was in his twenty-seventh year, and was attending the lessons of the Athenian philosophers. For this change, the reason seems to have been, that as Piso was the fittest person whom the author could find to support the doctrines of the old Academy, and as he had renounced his friendship during the time of the disturbances occasioned by the Clodian faction, it became necessary to place the conference at a period when they were fellow-students at Athens. The critics have observed some anachronisms in this last book, in making Piso refer to the other two dialogues, of which he had no share, and could have had no knowledge, as being held at a later period than that of the conference he attended.