Raja-Vidya: The King of Knowledge is a collection of transcribed lectures by Srila Prabhupada on the ninth chapter of the Bhagavad-gita.

This knowledge is the king of education, the most secret of all secrets. It is the purest knowledge, and because it gives direct perception of the self by realization, it is the perfection of religion. It is everlasting, and it is joyfully performed. ~ Bhagavad Gita 9.2

Rāja-vidyā means to know oneself what he is and act accordingly. That is called rāja-vidyā. If I do not know what I am, what is my position, then if I am in mistaken about my situation, then all activities, what I am doing, they are all mistaken. They are all illusion. Therefore this position, rāja-vidyā, means one should know himself, what he is, and act accordingly. Simply by knowing that "I am not this material body," that is not sufficient. You must act accordingly, that you are not material; you are spiritual. That spiritual activity is called Kṛṣ..., act in Kṛṣṇa consciousness, and that is called rāja-vidyā, the king of all education. ~ Srila Prabhupada's Lecture on BG 9.2 -- New York, November 22, 1966

• Original 1973 (First) unedited edition
• Author : His Divine Grace A.C. Bhaktivedanta Swami Srila Prabhupada
• 127 with 10 Color Plates in 14 Pages
• Format: Hard Cover, 5.25" x 7.75"