So if you are advanced, if you know what is the instruction of Kṛṣṇa by reading Bhagavad-gītā, you can preach to others. And if you have not read anything, suppose you do not know anything, then you can also preach. What is that? "Just become a devotee of Kṛṣṇa, my dear sir." That's all. This is also preaching. "Just surrender to Kṛṣṇa." You go door to door. If you cannot do anything, simply say, "My dear sir, you are very good man. Oh, you are very intelligent man. Chant Hare Kṛṣṇa."