The Arya Samaj was founded in Bombay in 1875 by Dayananda Saraswati, a Gujarati ascetic who had spent years studying Sanskrit grammar and the Vedas under traditional teachers before concluding that later Hindu practice, including image worship, caste by birth, child marriage and the authority of the Puranas, represented a departure from the Vedas' original teaching rather than a legitimate development of it. Dayananda argued that the four Vedas alone carried scriptural authority, and that they taught a single formless creator god, rejecting both polytheistic worship and later philosophical elaborations he considered later accretions.
Dayananda set out this position most fully in his book Satyarth Prakash, the Light of Truth, which became the Arya Samaj's foundational text alongside his commentaries on the Vedas themselves. The organization he founded held public preaching sessions and debates, ran schools, orphanages and gurukuls that taught Sanskrit learning alongside modern subjects, and, distinctively among nineteenth century Hindu reform movements, ran an active program of religious conversion and reconversion.
After Dayananda's death in 1883, the movement split over the balance between traditional Sanskrit education and modern scientific curriculum in its schools, but both branches continued the Samaj's characteristic mix of scriptural reform and social activism against caste restriction and child marriage, and the organization remains active in India today.