To each of the four Vedas were attached prose works, called Brahmanas, in order to explain the sacrifices and the duties of the priests.  Like the Four Vedas, the Brahmanas were held to be the very word of God.  The Vedas and the Brahmanas form the revealed Scriptures of the Hindus—­the sruti, literally “Things heard from God.”  The Vedas supplied their divinely-inspired psalms, and the Brahmanas their divinely-inspired theology or body of doctrine.  To them were afterward added the Sutras, literally “Strings of pithy sentences” regarding laws and ceremonies.  Still later the Upanishads were composed, treating of God and the soul; the Aranyakas, or “Tracts for the forest recluse;” and, after a very long interval, the Puranas, or “Traditions from of old.”  All these ranked, however, not as divinely-inspired knowledge, or things “heard from God” (sruti), like the Vedas and Brahmanas, but only as sacred traditions—­smriti, literally “The things remembered.”

Meanwhile the Four Castes had been formed.  In the old Aryan colonies among the Five Rivers of the Punjab, each house-father was a husbandman, warrior, and priest.  But by degrees certain gifted families, who composed the Vedic hymns or learned them off by heart, were always chosen by the king to perform the great sacrifices.  In this way probably the priestly caste sprang up.  As the Aryans conquered more territory, fortunate soldiers received a larger share of the lands than others, and cultivated it not with their own hands, but by means of the vanquished non-Aryan tribes.  In this way the Four Castes arose.  First, the priests or Brahmans.  Second, the warriors or fighting companions of the king, called Rajputs or Kchatryas, literally “of the royal stock.”  Third, the Aryan agricultural settlers, who kept the old name of Vaisyas, from the root vis, which in the primitive Vedic period had included the whole Aryan people.  Fourth, the Sudras, or conquered non-Aryan tribes, who became serfs.  The three first castes were of Aryan descent, and were honored by the name of the Twice-born Castes.  They could all be present at the sacrifices, and they worshipped the same Bright Gods.  The Sudras were “the slave-bands of black descent” of the Veda.  They were distinguished from their “Twice-born” Aryan conquerors as being only “Once-born,” and by many contemptuous epithets.  They were not allowed to be present at the great national sacrifices, or at the feasts which followed them.  They could never rise out of their servile condition; and to them was assigned the severest toil in the fields, and all the hard and dirty work of the village community.