The universal in its true and comprehensive meaning is a thought which, as we know, cost thousands of years to make it enter into the consciousness of men. The thought did not gain its full recognition till the days of Christianity. The Greeks, in other respects so advanced, knew neither God nor even man in their true universality. The gods of the Greeks were only particular powers of the mind; and the universal God, the God of all nations, was to the Athenians still a God concealed. They believed in the same way that an absolute gulf separated themselves from the barbarians. Man as man was not then recognised to be of infinite worth and to have infinite rights. The question has been asked, why slavery has vanished from modern Europe. One special circumstance after another has been adduced in explanation of this phenomenon. But the real ground why there are no more slaves in Christian Europe is only to be found in the very principle of Christianity itself, the religion of absolute freedom. Only in Christendom is man respected as man, in his infinitude and universality. What the slave is without, is the recognition that he is a person: and the principle of personality is universality. The master looks upon his slave not as a person, but as a selfless thing. The slave is not himself reckoned an 'I';--his 'I' is his master. The distinction referred to above between what is merely in common, and what is truly universal, is strikingly expressed by Rousseau in his famous 'Contrat Social,' when he says that the laws of a state must spring from the universal will (_volonté générale,_) but need not on that account be the will of all (_volonté de tous._) Rousseau would have made a sounder contribution towards a theory of the state, if he had always keep this distinction in sight. The general will is the notion of the will: and the laws are the special clauses of this will and based upon the notion of it.