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Satyarth Prakash (meaning "The Light of Truth") is a book written by Swami Dayananda Saraswati, the founder of the Arya Samaj, an Indian Hindu reform movement. It is an exposition of the philosophy of the Vedas, the sacred scriptures of Hinduism. The book has been translated into many languages and is considered to be one of the most important texts of the Arya Samaj.