A householder named Shaunaka approaches the great sage Angiras with a question that cuts to the heart of all learning:
What is that, by knowing which, everything else becomes known?
This question contains within it a radical dissatisfaction with ordinary knowledge. Shaunaka has presumably studied the Vedas, learned rituals, accumulated information. And none of it has answered the deepest question. What is the one thing that, if you knew it, would make sense of everything else?
Angiras makes a distinction that is among the most important in all of Indian thought. There are two kinds of knowledge, he says.
Apara Vidya — lower knowledge. This includes the four Vedas, phonetics, ritual, grammar, etymology, metre, and astronomy. These are not dismissed — they are given their proper place. But they are lower because they deal with the perishable.
Para Vidya — higher knowledge. The knowledge by which the imperishable Brahman is known. The knowledge that is not information about reality but direct recognition of what reality is.
That which cannot be seen, which cannot be grasped, which has no qualities, which is without colour, without eyes or ears, without hands or feet — the eternal, all-pervading, infinitesimal, imperishable — that is what the wise behold as the source of all beings.
The Mundaka goes on to give one of the most beautiful images in the Upanishads: two birds sitting on the same tree. One bird eats the fruits of the tree — sweet and bitter, pleasant and painful. The other bird simply watches, eating nothing.
You are both birds. The one that eats is the individual self, the jiva — experiencing pleasure and pain, caught in the flux of life. The one that watches is the Atman — the pure witness, untouched by anything that happens, eternally at peace.
Para Vidya is the recognition that you are the watching bird. That you have always been the watching bird. That all the eating — all the experience — was happening in front of you, not to you.
One knowing. And everything else becomes known.