Although Brahma created the principles of nescience as a matter of necessity for those living entities who were destined to ignorance by the will of the Lord, he was not satisfied in performing such a thankless task. He therefore created four principles of knowledge: sankhya, or empirical philosophy for the analytical study of material conditions; yoga, or mysticism for liberation of the pure soul from material bondage; vairagya, the acceptance of complete detachment from material enjoyment in life to elevate oneself to the highest spiritual understanding; and tapas, or the various kinds of voluntary austerities performed for spiritual perfection. Brahma created the four great sages Sanaka, Sananda, Sanatana and Sanat to entrust them with these four principles of spiritual advancement, and they inaugurated their own spiritual party, or sampradaya, known as the Kumara-sampradaya, or later on as the Nimbarka-sampradaya, for the advancement of bhakti. All of these great sages became great devotees, for without devotional service to the Personality of Godhead one cannot achieve success in any activity of spiritual value.