=The Stoic Writings.= Nearly all the writings of the early Stoics have been lost. Only fragments have been preserved from the writings of other men like Cicero, Plutarch, Sextus Empiricus, and Diogenes Laertius, and these men do not always distinguish between early and later Stoicism. The principal source of our knowledge of early Stoicism is Diogenes Laertius. The _Hymn to Zeus_ of Cleanthes is the most noteworthy fragment extant of the early period. Of the later Stoics of the Empire many writings have been saved: the ethical treatises and epistles of Seneca, the _Diatribes_ and _Encheiridion_ of Epictetus, and the _Meditations_ of Marcus Aurelius. The later Stoic writings transmit the teaching of the earlier leaders modified by many foreign influences. Such second-hand authorities as Cicero, Plutarch, Diogenes Laertius and Sextus Empiricus, and the Aristotelian commentators give reports so vitiated that it is doubtful if they report any element belonging to the earlier teaching. The doctrine of the Stoics, since the time of Chrysippus, however, is known beyond peradventure. =The Stoics and Cynics.= The Stoics tried to build up the life of the soul after the pattern of the virtuous Wise Man, whose outlines they borrowed from the transfigured and lofty form of Socrates. (Noack.) Their teaching is not merely a refinement and advance over the Cynic School as Epicureanism had been to the Cyrenaic School. Stoicism and Epicureanism used their sources in different ways. The Stoic would give up more than the Epicurean, and the negative side of his teaching is therefore greater; but in recompense he offers more in the shape of a comprehensive metaphysics. The Cyrenaic doctrine of pleasure became the corner stone of Epicureanism. The Cynic sensualistic rigorism became in the Stoic teaching a negative and relatively unimportant doctrine. While the Stoic distinction of virtue was not unproductive, the most influential aspect of Stoicism was its dissemination of humane culture. Thus, in contrast with the Cynics, the Stoics had a deep interest in scientific theory. The Stoic, less than the Cynic, contrasted the individual with the world. The Stoics have a more intelligent, freer, and milder morality. To the Cynics, external things have no value; to the Stoics, they have both a positive and a negative value. Beneath these differences there is the same self-sufficiency in virtue, the same withdrawal within, the same moral strength of will, the same antithesis between good and evil. Stoicism was original, but not enough so to mark the beginning of a new epoch.