In his published work, "The Self-Realization Fellowship Lessons", Yogananda gives "his in-depth instruction in the practice of the highest yoga science of God-realization. That ancient science is embodied in the specific principles and meditation techniques of "Kriya Yoga"." Yogananda taught his students the need for direct experience of truth, as opposed to blind belief. He said that "The true basis of religion is not belief, but intuitive experience. Intuition is the soul's power of knowing God. To know what religion is really all about, one must know God."