Hinduism is the major religion of India, practiced by more than 80% of the population. In contrast to other religions, it has no founder. Considered the oldest religion in the world, it dates back, perhaps, to prehistoric times. No single creed or doctrine binds Hindus together. Intellectually there is complete freedom of belief, and one can be monotheist, polytheist, or atheist. Hinduism is a syncretic religion, welcoming and incorporating a variety of outside influences. The most ancient sacred texts of the Hindu religion are written in Sanskrit and called the Vedas (vedah means “knowledge”). There are four Vedic books, of which the Rig-Veda is the oldest. It discusses multiple gods, the universe, and creation. The dates of these works are unknown (1000 B.C.?). Present-day Hindus rarely refer to these texts but do venerate them. The Upanishads (dated 1000–300 B.C.), commentaries on the Vedic texts, speculate on the origin of the universe and the nature of deity, and atman (the individual soul) and its relationship to Brahman (the universal soul). They introduce the doctrine of karma and recommend meditation and the practice of yoga. Further important sacred writings include the Epics, which contain legendary stories about gods and humans. They are the Mahabharata (composed between 200 B.C. and A.D. 200) and the Ramayana. The former includes the Bhagavad-Gita (Song of the Lord), an influential text that describes the three paths to salvation. The Puranas (stories in verse, probably written between the 6th and 13th centuries) detail myths of Hindu gods and heroes and also comment on religious practice and cosmology. According to Hindu beliefs, Brahman is the principle and source of the universe. This divine intelligence pervades all beings, including the individual soul. Thus the many Hindu deities are manifestations of the one Brahman. Hinduism is based on the concept of reincarnation, in which all living beings, from plants on earth to gods above, are caught in a cosmic cycle of becoming and perishing. Life is determined by the law of karma—one is reborn to a higher level of existence based on moral behavior in a previous phase of existence. Life on earth is regarded as transient and a burden. The goal of existence is liberation from the cycle of rebirth and death and entrance into the indescribable state of moksha (liberation). The practice of Hinduism consists of rites and ceremonies centering on birth, marriage, and death. There are many Hindu temples, which are considered to be dwelling places of the deities and to which people bring offerings. Places of pilgrimage include Benares on the Ganges, the most sacred river in India. Of the many Hindu deities, the most popular are the cults of Vishnu, Shiva, and Shakti, and their various incarnations. Also important is Brahma, the creator god. Hindus also venerate human saints. Orthodox Hindu society in India was divided into four major hereditary classes: (1) the Brahmin (priestly and learned class); (2) the Kshatriya (military, professional, ruling, and governing occupations); (3) the Vaishya (landowners, merchants, and business occupations); and (4) the Sudra (artisans, laborers, and peasants). Below the Sudra was a fifth group, the Untouchables (lowest menial occupations and no social standing). The Indian government banned discrimination against the Untouchables in the constitution of India in 1950. Observance of class and caste distinctions varies throughout India. In modern times work has been done to reform and revive Hinduism. One of the outstanding reformers was Ramakrishna (1836–1886), who inspired many followers, one of whom founded the Ramakrishna mission. The mission is active both in India and in other countries and is known for its scholarly and humanitarian works.