Hand in hand with this growth of the sacrificial system was the development of caste; the former was done away by the subsequent protest of Buddhism and the philosophic schools; but the latter has remained through all the stages of Hindu history.[42] Such was Brahmanism.  Its thraldom has never been equalled.  The land was deluged with the blood of slain beasts.  All industries were paralyzed with discouragement.  Social aspiration was blighted, patriotism and national spirit were weakened, and India was prepared for those disastrous invasions which made her the prey of all northern races.

It was in protest against these evils that Gautama and many able philosophers arose about 500 B.C.  Already the intellectual classes had matched the Brahmans by drawing upon Vedic authority for their philosophy.  As the Brahmans had produced a ritual from the Vedas, so the philosophers framed a sort of philosophic Veda in the Upanishads.  Men had begun to ask themselves the great questions of human life and destiny, “Whence am I?  What is this mysterious being of which I am conscious?” They had begun to reason about nature, the origin of matter, the relation of mortals to the Infinite.  The school of the Upanishads regarded themselves as an aristocracy of intellect, and held philosophy as their esoteric and peculiar prerogative.  It was maintained that two distinct kinds of revelation had been made to men.  First, that simple kind which was designed for priests and the common masses, for all those who regarded only effects and were satisfied with sacerdotal assumption and merit-making.  But, secondly, there was a higher knowledge which concerned itself with the origin of the world and the hidden causes of things.  Even to this day the Upanishads are the Vedas of the thinking classes of India.[43]

As the Brahmanas gave first expression to the doctrine of caste, so in the Upanishads we find the first development of pantheism and the doctrine of transmigration.  The conclusion had already been reached that “There is only one Being who exists:  He is within this universe and yet outside this universe:  whoe’er beholds all living creatures as in Him, and Him the universal spirit, as in all, thenceforth regards no creature with contempt.”

The language of Hindu speculation exhausts its resources in similes by which to represent personal annihilation.  Man’s origin and relations are accounted for very tersely by such illustrations as these:  “As the web issues from the spider, as little sparks proceed from fire, so from the One Soul proceed all breathing animals, all worlds, all the gods, all beings.”  Then as to destiny:  “These rivers proceed from the east toward the west, thence from the ocean they rise in the form of vapor, and dropping again, they flow toward the south and merge into the ocean.  And as the flowing rivers are merged into the sea, losing their names and forms, so the wise, freed from name and form, pass into the Divine spirit, which is greater than the great."[44] Another favorite illustration is that of the moon’s reflection in the water-jar, which disappears the moment the moon itself is hidden.  “If the image in the water has no existence separate from that of the moon,” says the Hindu, “how can it be shown that the human soul exists apart from God?”