Gradually, however, the castes began to lose their flexible nature, and before the birth of Buddha in the year 600 B. C. they had already acquired a hereditary character. The teachings of Buddhism had the tendency to break down the hereditary barriers of caste, and during a thousand years of its reign the people of India had forgotten their caste boundaries. “Around 600 A. D. Buddhism began to decline and the Brahman priests gained fresh prestige. They set up the different castes on the old hereditary lines once again, and, except for a few local breaks through the appearance of such leaders as Nanak in Punjab and Chaityna in the South, the spirit of caste has prevailed throughout Hindu India since the decline of Buddhism.” The greatest champion of the lower classes who has appeared in recent times is the peaceful leader of India’s silent revolution, Mahatma Gandhi. He has spoken and written against untouchability and its allied evils more bitterly and longer than against other vital political and economic wrongs of the country. He has told his countrymen time and again that India’s soul cannot become pure so long as untouchability stays amongst the Hindus to defile it. And as a proof of his own sincerity in the matter he has adopted in his own family an untouchable girl whom he calls the joy of the household. The evils of caste are quite manifest. It has tended to divide the Hindu community into various groups and thus destroyed among them unity of feeling which alone could insure national strength. Lack of united power opened the way for foreign invasions, which, again, has resulted in dragging India down from her former place of glory to her present state of humiliation and ruin. Yet alongside with the many evils of India’s caste system several advantages have accrued from it. Its existence has tended to make the people of India conservative and tolerant. With the institution of caste they felt so well fortified within themselves that they did not fear the influx of new ideas into their midst. India offered a safe and welcome home to the oppressed minorities from other lands. The Parsis and Jews came and settled there. They were not merely tolerated but welcomed by the Hindus, because the latter, assured of their own wonderful powers of resistance, had nothing to fear from outside influences. The Hindu caste system may be described as “the social formulation of defence minus all elements of aggression.” Since the beginning of her history India has been subjected to numerous invasions, but she has stood against them successfully. In the cultural sense India, instead of being conquered, “has always succeeded in conquering her conquerors.” The invaders belonging to different civilizations and races have come and disappeared, one after the other; but India still survives.[32]