Most mantras are drawn from sruti, used for rites of worship, both public and domestic, as well as personal prayer and japa. It is a remarkable tribute to Hindu culture that so much of sruti was preserved for thousands of years without alteration by means of oral instruction from guru to shishya, generation after generation. In the Veda tradition this was accomplished by requiring the student to learn each verse in eleven different ways, including backwards. Traditionally sruti is not read, but chanted according to extremely precise rules of grammar, pitch, intonation and rhythm. This brings forth its greatest power. In the sacred language of shruti, word and meaning are so closely aligned that hearing these holy scriptures properly chanted is magical in its effect upon the soul of the listener.