Everything we can know. This human form of body is specially meant for that purpose. You can understand what you are, what is this material nature, what is God and how we are related, how things are going on. Everything is there, but we are so foolish that we do not take care. We live like cats and dogs, eat something and sleep and have sexual intercourse and then we are afraid always and then die. This is cats' and dogs' life. Real life is to know, athato brahma jijnasa. That is real life, human life. One must be inquisitive to understand the Absolute Truth, brahma-jijnasa, not inquiring in the market, "What is the rate of share? What is the rate of rice? No, not for this inquiry. Jijnasuh sreya uttamam. To inquire about the Absolute Truth, uttamam, beyond this material nature. Udgata tamam. This material nature is called tama. Tamaso ma jyotir gama. These are the Vedic injunctions.
Lecture on Bhagavad-gita 13.16, Bombay, 10 October, 1973