transparent to others, and unbearably so
A man undergoing intensive psychotherapy discovers that he is brittle, hollow, and transparent to others, and becomes either transcendentally enlightened or schizophrenic.
Context
The Man Who Began to Suspect He Was Made of Glass literalizes the cage of self as its opposite fear — not sealed off but seen straight through, "brittle, hollow, and transparent to others" — and leaves it open whether that total legibility is enlightenment or madness. It rhymes hard with Orin sealed inside the glass tumbler (184): the self as glass, on view and untouchable at once.