Spiritual knowledge must be received through disciplic succession from a qualified spiritual master. The Bhagavad-gita (4.1-3) describes the disciplic succession, and (4.34) teaches that one should approach a guru with humility, render service, and inquire submissively. The guru is not God but is the representative of God. The Science of Self-Realization (Chapter 2) explains that self-made spirituality is not authentic and that the guru must be in disciplic succession.