To be sure, before this equalitarian ideal could be embodied in a social program it had to await the coming of the modern age with its open doors, its freer movements of thought and life, its belief in progress, its machinery of change. But even in the stagnation of the intervening centuries the old Stoic-Christian ideal never was utterly forgotten. Lactantius, a Christian writer of the fourth century, said that God, who creates and inspires men, "willed that all should be equal." [3] Gregory the Great, at the end of the sixth century, said that "By nature we are all equal." [4] For ages this spiritual insight remained dissociated from any social program, but now the inevitable connection has been made. Old caste systems and chattel slavery have gone down before this ideal. Aristotle argued that slavery ethically was right because men were essentially and unchangeably masters or slaves by nature. Somehow that would not sound plausible to us, even though the greatest mind of all antiquity did say it. Whatever may be the differences between men and races, they are not sufficient to justify the ownership of one man by another. The ideal of equality has wrecked old aristocracies that seemed to have firm hold on permanence. If one would feel again the thrill which men felt when first the old distinctions lost their power, one should read once more the songs of Robert Burns. They often seem commonplaces to us now, but they were not commonplaces then: "For a' that and a' that, Their dignities, and a' that; The pith o' sense and pride o' worth Are higher rank than a' that!"