Basically speaking, when you say “I am,” you begin to ask yourself the question, “Who said that?” You might say, “I said that.” But then you ask, “Who are you?” And when you look, you find it is very difficult to find out who that actually is. You might timidly come back to saying your name, thinking that this is who is speaking, but beyond the name that was given to you, nothing really exists. You may think that you exist because your name is so-and-so, or because your driver’s license says so-and-so. But if you look beyond such things, and beyond beyond, you find that there is no substance. That is ultimate prajna: it is the discovery of egolessness, which frees you from fixation.
From The Profound Treasury of the Ocean of Dharma. Volume Two: The Bodhisattva Path of Wisdom and Compassion by Chögyam Trungpa, page 265