The difficulty is that the instruction of Bhagavad-gītā, they do not follow. The instruction of Bhagavad-gītā is evaṁ paramparā-prāptam imaṁ rājarṣayo viduḥ (BG 4.2). One has to learn from the disciplic succession. Tad viddhi praṇipātena paripraśnena sevayā (BG 4.34). You have to learn from a person by full surrender. You cannot surrender to a third-class man. Unless one is very advanced, naturally you surrender. But this is the process. Unless you are prepared to surrender . . . surrender means you approach somebody where your intelligence is nothing; therefore you have to surrender. Tad viddhi praṇipātena paripraśnena sevayā.
Sevā and dayā. There are two words. Sevā is offered to the superior person, sevā, service. And dayā is offered to an inferior person. Who is less than you—he requires your mercy—that is dayā. But who is superior than you—who requires your service—that is called sevā. This is the difference between sevā and dayā. But people do not know. They are trying to amalgamate dayā and sevā. No. Dayā to the inferior person. Just like a child, he requires your dayā, the dayā of the parents, mercy of the parents. But a guru, he requires your sevā, service. So you have to approach, sevā, praṇipāta, surrender, sevā; then you can question. Don't question unnecessarily, waste your time, where you cannot surrender, where you cannot render your service. This is the process. Tad viddhi praṇipātena paripraśnena sevayā (BG 4.34). Then you can derive some benefit from the realized person. Upadekṣyanti te jñānaṁ jñāninas tattva-darśinaḥ.