Now, Kṛṣṇa is concluding these different types of yajña. He says that śreyān dravyamayād yajñāj jñāna-yajñaḥ parantapa. Jñāna-yajña, jñāna-yajña means... This is jñāna-yajña, which we are doing here. We are discussing Bhagavad-gītā very scrutinizingly and trying to understand every verse with reference to the Vedic reference and as far as our logic and argument goes. So this is called jñāna-yajña.
And dravyamaya-yajña means, just like yesterday, day before yesterdays, discussed that in the altar of fire we have to sacrifice clarified butter, grains, or sometimes animal sacrifice. They are called dravyamaya-yajña. So Kṛṣṇa says, śreyān dravyamayād yajñāt. That dravyamaya, that sacrificing goods or other things in the yajña, from that type of yajña, śreyān dravyamayād yajñāj jñāna-yajñaḥ parantapa. Jñāna-yajña, this philosophical discussion, logical discussion of the aim of life from authorized books like Bhagavad-gītā, Śrīmad-Bhāgavatam, if we have discussion, this is called jñānamaya-yajña, with knowledge, jñānamaya-yajña.
So why jñānamaya-yajña is preferred? Sarvaṁ karmākhilaṁ pārtha jñāne parisamāpyate. Because after all, we have to acquire that knowledge which will make me a surrendered soul to the Supreme. That's it. Bahūnāṁ janmanām ante jñānavān māṁ prapadyate (BG 7.19). So jñāna also means that to understand our position, to understand what is God, to understand what is our relationship with God, to understand why we are in this material world and what is our next life, wherefrom we have come, where we have the right knowledge, you can understand all these things. And when you understand everything, the path is clear, you can clearly understand that "I am the part and parcel of the Supreme; therefore my duty is to render transcendental service to the Supreme." That is the highest yajña, highest jñāna, knowledge, knowledge, yajña. So Kṛṣṇa advises that jñānamaya-yajña, sacrifice... Sacrifice.