Rita is the cosmic order in Hindu religion that guides not only the individual life of man, but also the totality of universal life. So, a god is sometimes called Ritavan and a goddess Ritavati. The god Varuna is supposed to be the custodian of Rita, which, according to Vedic seers, is praised and glorified even by the devas.
The Rig Veda calls Vishnu ritasya garbha, the embryo of Rita. The dawn, the sun, the moon, in fact the entire universe is based on Rita. The twenty-third sukta of the fourth Rig Vedic mandala, addressed to the god Indra, ends with the glorification of Rita. As a moral principle it encompasses the psychological life of individuals. As the cosmic Order or eternal Law it is responsible for the triumph of good over evil and light over darkness.
Rita integrates chaos into cosmos, gives order to the universe and shows the righteous path for the mind to follow. It is the psychological principle teaching man how to lead a moral life. Thus we can see that according to the Vedic seers, the same ideal functions as the guiding principle for individual as well as universal life. That is why in the first sukta of the Rig Veda itself, addressed to Agni, the sages call their deity ‘Rtasya didivim’, the illuminator of truth.
Source - Excerpts from The Concept of God in the Vedas by Swami Tattwamayananda published in June 2005 issue of Prabuddha Bharata