Rta, or Rta(m), (Sanskrit, “fixed order, rule”) in Hinduism is the sense of fundamental order and balance that exists in the universe and must be observed and sustained through appropriate sacrifices, rituals, and behaviors.
The word rta is related to rtu, the seasons, which recur regularly outside of the control of man; and, for the matter, the gods also. Mitra and Varuna are invoked in the Vedas as guardians of rta, but they are never regarded or described as its creator or controller. Rta is deeper and more fundamental than the gods, and anticipates the impersonal law of karma, and the pervasive rule of dharma. A.G.H.
Bowker, John, The Oxford Dictionary of World Religions, New York, Oxford University Press, 1997, pp. 825-826