As long as there exist in social life certain laws, manners, and customs by which the civilized man is distinguished from the savage, the gentleman from the cowherd, the high-born dame from her lowly maid, so long will caste, which is nothing more or less than social grades, complicate the lives and destinies not only of the races of the East, but of the West. The three great problems which yet remain to be solved by the British in India are to do away with the degradation of man by caste, the bondage of woman by custom, and the deterioration of childhood through the influence of the one and the other. Caste on Indian soil was not in its beginning an entirely arbitrary institution; it was at first the natural expression of a high-bred and highly-sensitive race toward an inferior and savage population among which they had settled. It took centuries before caste was established on Indian soil, and nearly a thousand years before it became incorporated in the sacred books of the Brahmans in its present form. But the moment that divine authority was claimed for it, that moment it became to the God-fearing races of the East a law so subtle, so intricate, and yet so absolute, that the most daring as well as the most abject could not hope to escape its iron rule. From the remotest times there has been a ceaseless march of tribes and races into the vast peninsula called Hindostan, from which there is no easy outlet, east or west, north or south; all points are equally difficult and impassable--mountain-barriers on the north, with ranges of mountains and circling seas on every other side. Nevertheless, pouring across the Indus and straggling down the narrow defiles and passes of the Himalayas, came wave after wave of immigration, pushing the earlier populations farther and farther into the hills and forest-boundaries of the occupied land. Each wave, borne down by the later arrival, disappeared or retreated deeper and deeper into the heart of the country till the whole of India was over-flooded by the great Aryan invasion. In no part of the world are there found so many remains of distinct tribes and races of men as in Hindostan proper. Everywhere in the forests, in the most inaccessible mountain-regions of the peninsula, and all along the sea-coast, are tribes and races who seem to have been hemmed in where we now find them. The vast plains of the regions of the Indus and the Ganges afforded no place of refuge to the retreating barbarians. Hence, with the exception of some few who were absorbed into the population of Lower Bengal, the Aryans drove all before them, even the Tamuls, a partly-civilized people, who, having swept the earlier inhabitants southward, were in their turn forced south.