यावानर्थ उदपाने सर्वतः संप्लुतोदके।तावान्सर्वेषु वेदेषु ब्राह्मणस्य विजानतः॥
yāvān artha udapāne sarvataḥ samplutodaketāvānsarveṣu vedeṣu brāhmaṇasya vijānataḥ
Word by word
The verse says
A well is useful until the whole place floods. That is how much use all the scriptures are to someone who has actually seen.
In plain words
One image, and it settles the argument.
A well is genuinely valuable. You dig it, you maintain it, you depend on it. Then the flood comes and covers everything, and the well has not become wrong. It has become beside the point.
That, Krishna says, is scripture to someone who has seen directly.
Where you've felt this · in study
You learn a route by memorising every turn, and it works. Years later you know the whole area, and you notice you have not thought about the list of turns in a long time. It was never false. You simply went past needing it.
Going deeper
This is one of the boldest images in the Gita, and the tradition has argued about it for a very long time.
The reading that does least violence to the words is this: scriptures are instruments, and instruments are for people who need them. Direct knowledge does not contradict the texts. It makes consulting them unnecessary, the way a flood makes a well unnecessary — not by disproving the water in it.
Some commentators soften this considerably, reading it as applying only to the ritual portions of the Veda rather than to scripture as such. Others take it at full strength. The line supports both, and a reader should know the argument exists rather than be handed one side.
What is not in dispute is the direction of travel. The Gita consistently ranks seeing above being told — 2.29 said even hearing this leaves you not knowing it, and 4.34 will send Arjuna to a teacher rather than to a text.
And there is something quietly humbling in a scripture saying this about scripture, including itself.