The Bhagavad-gita is the essence of all Vedic knowledge. It is the first book of spiritual values, as the Upanisads are. The Vedanta philosophy is the subject matter for study by the spiritual graduates. Only the postgraduate spiritual student can enter into the spiritual or devotional service of the Lord. It is a great science, and the great professor is the Lord Himself in the form of Lord Sri Caitanya Mahaprabhu, and persons who are empowered by Him can initiate others in the transcendental loving service of the Lord. SB 1.4.25
