In the middle of the first millennium B.C., an ossified Brahmanism was challenged by heterodox, i.e., non-Vedic, systems, notably Buddhism and Jainism. The priestly elite responded by creating a synthesis that accepted yogic practices and their goals, recognized the gods and image worship of popular devotional movements, and adopted greater concern for the daily life of the people. There was an increase in writings, such as the Laws of Manu (see Manu), dealing with dharma, or duty, not only as applied to the sacrifice but to every aspect of life. Their basic principle is varna-ashrama-dharma, or dharma in accordance with varna (class or caste) and ashrama (stage of life). The four classes are the Brahmans, Kshatriyas (warriors), Vaishyas (farmers and merchants), and Shudras (laborers). The four stages of life are brahmacharya or celibate student life (originally for study of the Veda), grihastha or householdership, vanaprastha or forest hermitage, and sannyasa, complete renunciation of all ties with society and pursuit of spiritual liberation. (In practical terms these stages were not strictly adhered to. The two main alternatives have continued to be householdership and the ascetic life.) The entire system was conceived as ideally ensuring both the proper function of society as an integrated whole and the fulfillment of the individual's needs through his lifetime.
The post-Vedic Puranas deal with these themes. They also elaborate the myths of the popular gods. They describe the universe as undergoing an eternally repeated cycle of creation, preservation, and dissolution, represented by the trinity of Brahma the creator, Vishnu the preserver, and Shiva the destroyer as aspects of the Supreme.