What did David believe was the most important condition that made it possible for him to go on living? Why do you think David believed this?

David believed that Johannes was his most important reason for living.

He had forgotten the most important condition that made it possible for him to go on living: that he should never again grow fond of anyone. When Johannes died he thought he would die too. But when he had recovered and knew he was not going to die, he realized that he must never, never care for anyone again – never.