Such an interpretation of instinct introduces us to a new principle—self-interest; and this was, in fact, recognised on all hands as the foundation of right conduct; it was about the question, What is our interest? that the ancient moralists were disagreed. The Cynics apparently held that, for every being, simple existence is the only good, and therefore with them virtue meant limiting oneself to the bare necessaries of life; while by following Nature they meant reducing existence to its lowest terms, and assimilating our actions, so far as possible, to those of the lower animals, plants, or even stones, all of which require no more than to maintain the integrity of their proper nature. Where the Cynics left off the Stoics began. Recognising simple self-preservation as the earliest interest and duty of man, they held that his ultimate and highest good was complete self-realisation, the development of that rational, social, and beneficent nature which distinguishes him from the lower animals.[49] Here their teleological religion came in as a valuable sanction for their ethics. Epictêtus, probably following older authorities, argues that self-love has purposely been made identical with sociability. ‘The nature of an animal is to do all things for its own sake. Accordingly God has so ordered the nature of the rational animal that it cannot obtain any particular good without at the same time contributing to the common good. Because it is self-seeking it is not therefore unsocial.’[50] But if our happiness depends on external goods, then we shall begin to fight with one another for their possession:[51] friends, father, country, the gods themselves, everything will, with good reason, be sacrificed to their attainment. And, regarding this as a self-evident absurdity, Epictêtus concludes that our happiness must consist solely in a righteous will, which we know to have been the doctrine of his whole school.