This is a lecture from the book Sri Isopanisad (Mantra 1) that Srila Prabhupada gave on April 29, 1970 in Los Angeles.
But we have to take knowledge from Kṛṣṇa. Our process is that. We don't accept any other process of knowledge. Our knowledge is to receive the knowledge from the authority, and that is fact. That is first-class knowledge. If you get one authority who can speak on the subject matter, and if you take that knowledge, that is perfect. There are three kinds of processes to receive knowledge. The first: we believe direct sense perception, pratyakṣa. Just like somebody says, "Can you show me God?" That means they are Pratyakṣavādi. They want to see everything direct, experience everything directly. This class of men says that "Can you show me God?" But this is not first-class knowledge. Suppose you ask me, "Can you show me God?" I say, "Yes, I can show you God." "Show me." "I'll show you. So this is God." Will you believe it? Suppose you are asking me, "Can you show me God?" I say, "Yes, I can show you." "What is that God?" "Here is God," I say. So will you accept it that this microphone is God? What is the answer? Huh? Why no?
Viṣṇujana: Doesn't have the qualifications.
Prabhupāda: No. If you ask me, "Can you show me God," I show anything, whatever I like, "Yes, here it is, God..." Or why God? Suppose you go to a store. So you ask something, "Can you give me gold?" He'll give you a scrap of iron: "Yes, here it is gold. Take it." So what you will say? What will be the answer? Huh? If you ask... You go to a storekeeper. You do not know where to purchase gold, but you are in need of some gold, and you go to a storekeeper and ask him, "Have you got gold in stock?" So he'll immediately understand that here is a rascal number one, because he has come to purchase gold in a store, ordinary store. If one has to purchase gold, he must go where gold is sold. But he has come to ordinary store to purchase; therefore he's a first-class rascal. So therefore he'll try to cheat him: "Here is a gold." He gives a piece of iron. Then what he will say? He will accept that iron as gold? Huh? Why no? He does not know what is gold, and he has gone to a store to purchase it, and he gives him one piece of iron, "Here is gold." So he'll purchase it. He'll be cheated. Similarly, those rascals who say that "Can you show me God?" so they must know what is God; otherwise he'll be cheated. That is being done.
So if you want to purchase gold, at least you must have some preliminary knowledge what is gold. Characteristics. Just like in the chemical laboratory, they test. Suppose in the pharmacy or... This is the government law, that whatever you accept some chemicals or some drug, you must test it, and the testing characteristics are stated there. Just like soda bicarb: the color is like this, the constitution is like this, the reaction is like this, the taste is like this. So a chemist in the laboratory corroborate the characteristic, then accept it, "Yes, it is soda bicarb." Similarly, if you want to know God, of if you want to see God, then first thing is that you must know what is the characteristics of God. Otherwise, if you go to another rascal and you ask him, "Can you show me God," and he shows you something nonsense, you accept it God, is that very nice thing? This is going on. "I want to see God."