Yājñavalkya was the most famous sage of his time. He had two wives — Kātyāyanī, who was ordinary, and Maitreyī, who was a brahmavādinī, a woman who asked questions about the Self. One day Yājñavalkya announced he was leaving householder life to become a wandering sannyāsī. Before he left, he wanted to divide his property between his two wives, so that neither would quarrel after he was gone.
Maitreyī listened to the arrangement. She asked him a question.
Sir, she said, if this whole earth, full of wealth, were mine, would I become immortal through it?
Yājñavalkya said — no. Your life would be what the lives of the wealthy are. There is no hope of immortality through wealth.
Then, she said — what use is this to me? Teach me what you know that is worth having.
This is the moment the dialogue becomes an Upaniṣad. Yājñavalkya, moved, sits back down and begins to teach her. He says: not for the sake of the husband is the husband dear, but for the sake of the Self. Not for the sake of the wife is the wife dear, but for the sake of the Self. Not for the sake of wealth is wealth dear, but for the sake of the Self. Everything we think we love, we love because the Self shines through it.
This is not a cold teaching. He is not saying she should not love him. He is saying that her love, rightly understood, is pointing at something deeper than him — at the Self that makes him loveable. When she sees that, her love will not end; it will steady. When he dies, the love will not end; it will remain, pointing at what was always behind him.
He goes further. The Self, he says, is like a lump of salt dropped in water. You cannot find the salt anywhere — inside the water, outside the water, on the surface. It is everywhere in the water, seamless. That is the Self. Not a thing you can find among the other things. A reality in which the other things swim.
Maitreyī listens. The teaching ends. Yājñavalkya leaves for the forest. She does not, we are told, inherit the property. She inherits the teaching instead. In the Upaniṣadic world, that is a much larger inheritance.
The dialogue is one of the earliest, anywhere, in which a woman is recorded as asking the question that cracks open the whole metaphysical edifice. She asks it not as a philosopher, but as a wife being left. Which is to say — she asks it from her life. That is the only place it has ever been worth asking from.