Surgery takes de basic imperative of the medical profession to its outermost border, where the human makes contact with the divine. When a person is clubbed violently on the head, he collapses and stops breathing. Some day, he will stop breathing anyway. Murder simply hastens a bit what God will eventually see to on His own. God, it may be assumed, took murder into account; He did not take surgery into account. He never suspected that someone would dare to stick his hand into the mechanism He had invented, wrapped carefully in the skin, and sealed away from human eyes. Thomas first positioned his scalpel on the skin of a man asleep under anaesthetic, then breached the skin with a decisive incision, and finally cut it open with a precise and even stroke (as if it were a piece of fabric - a coat, a skirt, a curtain) he experienced a brief but intense feeling of blasphemy. Then again, that was what attracted him to it! That was the "Es muss sein!" rooted deep inside him, and it was planted there not by chance, not by the chief's sciatica, or by anything external.
A doctor is someone who consents to spend his life involved with human bodies in all that they entail. That basic consent (and not talent or skill) enables him to enter the dissecting room during he first year of medical school and persevere for the requisite number of years.
In The Unbearable Lightness of Being, Milan Kundera