One of the dearest, perhaps the dearest friend of Lucretius, was this Memmius, who had been his school-fellow, and whom, it is supposed, he accompanied to Bithynia, when appointed to the government of that province(431). The poem _De Rerum Natura_, if not undertaken at the request of Memmius, was doubtless much encouraged by him; and Lucretius, in a dedication expressed in terms of manly and elegant courtesy, very different from the servile adulation of some of his great successors, tells him, that the much desired pleasure of his friendship, was what enabled him to endure any toil or vigils— “Sed tua me virtus tamen, et sperata voluptas Suavis amicitiæ, quemvis ecferre laborem Suadet, et inducit nocteis vigilare serenas.” The life of the poet was short, but happily was sufficiently prolonged to enable him to complete his poem, though, perhaps, not to give some portions of it their last polish. According to Eusebius, he died in the 44th year of his age, by his own hands, in a paroxysm of insanity, produced by a philtre, which Lucilia, his wife or mistress, had given him, with no design of depriving him of life or reason, but to renew or increase his passion. Others suppose that his mental alienation proceeded from melancholy, on account of the calamities of his country, and the exile of Memmius,—circumstances which were calculated deeply to affect his mind(432). There seems no reason to doubt the melancholy fact, that he perished by his own hand. The poem of Lucretius, _De Rerum Natura_, which he composed during the lucid intervals of his malady, is, as the name imports, philosophic and didactic, in the strictest acceptation of these terms. Poetry, I think, may chiefly be considered as occupied in three ways.—1. As describing the passions of men, with the circumstances which give birth to them.—2. As painting images or scenery.—3. As communicating truth. Of these classes of poetry, the most interesting is the first, in which we follow the hero placed at short intervals in different situations, calculated to excite various sympathies in our heart, while our imagination is at the same time amused or astonished by the singularity of the incidents which such situations produce. Those poems, therefore, are the most attractive, in which, as in the _Odyssey_ and _Orlando_, knights or warriors plough unknown seas, and wander in strange lands—where, at every new horizon which opens, we look for countries inhabited by giants, or monsters, or wizards of supernatural powers—where, whether sailing on the deep, or anchoring on the shore, the hero dreads— “Lest Gorgons, rising from infernal lakes, With horrors armed, and curls of hissing snakes, Should fix him, stiffened at the monstrous sight, A stony image in eternal night.” These are the themes of surest and most powerful effect: It is by these that we are most truely moved; and it is the choice of such subjects, if ably conducted, which chiefly stamps the poet—