Bitter: One of the Four Human Taste Buds

Much of your pain is the bitter potion by which the physician within you heals your sick self.
Kahlil Gibran

In The Desert

In the desert
I saw a creature, naked, bestial,
Who, squatting upon the ground,
Held his heart in his hands,
And ate of it.
I said: "Is it good, friend?"
"It is bitter-bitter," he answered;
"But I like it
Because it is bitter,
And because it is my heart."
Stephen Crane