Srimad Bhagavatam Canto 03, Chapter 12, Text 04

SB 3.12.4

sanakam ca sanandam ca
 sanatanam athatmabhuh
sanat-kumaram ca munin
 niskriyan urdhva-retasah
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
In the beginning, Brahma created four great sages named Sanaka, Sananda, Sanatana and Sanat-kumara. All of them were unwilling to adopt materialistic activities because they were highly elevated due to their semen’s flowing upwards.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
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.
Srimad Bhagavatam Canto 03, Chapter 12, Text 03
Srimad Bhagavatam Canto 03, Chapter 12, Text 05