[Sidenote: Seneca’s philosophical writings.] Seneca’s philosophical writings fall naturally into three divisions: the formal treatises on ethical subjects, the twenty books of _Ethical Letters_ (_Epistulæ Morales_), addressed to Lucilius[93], and the _Studies of Nature_ (_Quæstiones Naturales_), in seven books. The last-mentioned work, addressed to Lucilius, and written between 57 and 64 A. D., is by no means a complete treatise on nature. Two books treat of astronomy, two of physical geography, and four of meteorology; for Book IV should properly be divided into two books, one on physical geography, the other on meteorology. These subjects are treated from the point of view of the Stoics, without any original investigation by Seneca, who derives his information entirely from books. The work was very popular in the Middle Ages, but is of no scientific value. Seneca’s chief interest was in ethics, and he uses the phenomena of nature as texts for his ethical views. The formal treatises on ethics discuss such subjects as _Anger_ (_De Ira_, in three books), _The Shortness of Life_ (_De Brevitate Vitæ_), _Clemency_ (_De Clementia_). _The Happy Life_ (_De Vita Beata_), _Consolation_ (_De Consolatione_, three independent treatises addressed to different persons), and _The Giving and Receiving of Favors_ (_De Beneficiis_, an elaborate treatise in seven books). The _Letters_ treat of similar subjects in a somewhat less formal way. These works show that Seneca had studied with great diligence the works of previous writers on such subjects, especially those of the Stoics, though the writings of Epicureans had been by no means neglected. The moral teaching is, in the main, sound and wise, but there is little originality of thought. The style is vigorous and effective, though artificial and rhetorical; but these latter qualities were so natural to Seneca, in common with other writers of his day, that they do not detract from the sincerity of the sentiments expressed. Seneca is the most complete exponent of the Stoic philosophy as it developed at Rome. He is not so much a speculative thinker as a giver of practical advice for the conduct of life. Like most, if not all, the Roman Stoics, he is a preacher and teacher; and as such he is of the highest interest and importance. His works were much read in his own time and in the years immediately following, though Quintilian and others who wished to revive the Latin of Cicero found fault with their style. Their popularity continued unabated for centuries, and their high moral tone led to the belief that Seneca was a Christian. This belief was strengthened by the composition, at a comparatively early date, of a series of fourteen letters supposed to have been exchanged between Seneca and the Apostle Paul. These letters are, however, obviously forgeries, and possess no literary merit. Seneca’s influence did not die with the death of the ancient civilization, but