"The mind's position is accepting and rejecting. Intellect helps the mind what to reject and what to accept. And that intelligence is of the soul. That ground of intelligence is the soul. First of all bodily concept is gross life, ordinary, like animals, they do not know except the body. Higher than bodily concept of life, the exercise of the mind, mental speculation. That mental speculation is adjusted by intelligence and that intelligence belongs to the soul. Therefore soul is the ultimate and soul is the part and parcel of God. Therefore God is the supreme. So the mental speculation or the evolution of mental exercise when it comes to the summit, that is God realization. Vāsudevaḥ sarvam iti, sa mahātmā sudurlabhaḥ (BG 7.19). When one realizes 'God is everything,' that mahātmā, that great soul is very rare. That is the statement in Bhagavad-gītā. Mahātmā means whose mind is great. The mind is great. He's not thinking ordinary things. He's thinking of greater subject matter. They are called mahātmā, broader minded, broad-minded."
(Srila Prabhupada Conversation with Dr. Weir of the Mensa Society,