The accumulated and transmitted experience of successive generations has taught man that by uniting with other men his preservation is better secured and his well-being increased. Thus out of this same strife for existence, carried on against surrounding nature, and against individuals of their own species, the social instinct has been developed among men, and has completely transformed the conditions of their life. Through co-operation man has been enabled to evolve out of animalism, has risen to great power, and elevated himself to such a degree above the other animals, that metaphysical philosophers have believed it necessary to invent for him an immaterial and immortal soul. Many concurrent causes have contributed to the formation of this social instinct, that starting from the animal basis of the instinct for the preservation of the species, has now become so extended and so intense that it constitutes the essential element of man's moral nature. Man, however he evolved from inferior animal types, was a physically weak being, unarmed for the fight against carnivorous beasts. But he was possessed of a brain capable of great development, and a vocal organ, able to express the various cerebral vibrations, by means of diverse sounds, and hands adapted to give the desired form to matter. He must have very soon felt the need and advantages of association with his fellows. Indeed it may even be said that he could only rise out of animalism when he became social, and had acquired the use of language, which is at the same time a consequence and a potent factor of sociability.