Buddhi-yoga itself is action in Krsna consciousness; that is the highest intelligence. Buddhi means intelligence, and yoga means mystic activities or mystic elevation. When one tries to go back home, back to Godhead, and takes fully to Krsna consciousness in devotional service, his action is called buddhi yoga. In other words, buddhi-yoga is the process by which one gets out of the entanglement of this material world.
Bg 10.10 Purport
"One who is perfectly intelligent, after many many births of culturing knowledge he comes to Me and surrenders." Yes. Vasudevah sarvam iti: [Bg. 7.19] "O Krsna, you are everything." That is the highest intelligence.
Bhagavad-gita 4.19-25 -- Los Angeles, January 9, 1969
