तद्विद्धि प्रणिपातेन परिप्रश्नेन सेवया।उपदेक्ष्यन्ति ते ज्ञानं ज्ञानिनस्तत्त्वदर्शिनः॥
tad viddhi praṇipātena paripraśnena sevayāupadekṣyanti te jñānaṃ jñāninas tattva-darśinaḥ
Word by word
The verse says
Learn it by going and bowing, by asking properly, by being of use. Those who know, who have seen how things are, will teach it to you.
In plain words
The most practical instruction in the Gita, and it has three parts.
Praṇipāta - bowing, going down. Paripraśna - asking thoroughly, all around the question. Sevā - service, being useful to them.
And notice the order. The bowing comes before the asking.
Where you've felt this · in study
You want to learn from a man who actually knows the trade. You turn up early, carry things, sweep up, and ask your questions afterwards. Six months in, he starts telling you things you did not know enough to ask about.
Going deeper
This verse is the Gita telling you that it is not enough on its own, and it is remarkable that it does.
Everything so far has been transmitted through a text. Here Krishna sends Arjuna - and the reader - to a person: those who have seen how things actually are. Seers, not scholars.
The three conditions are in a deliberate order, and each one removes an obstacle.
Praṇipāta - prostration - removes the posture in which you are sizing the teacher up rather than learning from them. It is the physical form of the not-fault-finding asked for at 3.31.
Paripraśna is what balances it. Not blind acceptance: thorough questioning, from every side. The Gita wants both, and the order matters - the bowing first, so that the questioning is not a contest.
Sevā - service - is the one modern readers find hardest, and it is doing something specific. Time spent being useful to someone is time spent near them, and this kind of knowledge transmits by proximity rather than by explanation.
It should also be said plainly that this structure has been abused wherever it exists. A tradition that requires prostration to a teacher has handed that teacher a great deal. Paripraśna is the safeguard the text itself supplies, and it is worth holding on to.