Boredom

Boredom - his name for the relentless enemy that has stalked him everywhere - has lessened with age, Mr Greene said. He has described, in terrible detail, the peculiar torture it once caused him. A young, and more despairing Graham Greene found his boredom so unbearable that, in 1923, he played Russian Roulette, alone, with a loaded revolver "to make the discovery that it was possible to enjoy again the visible world by risking its total loss." It was boredom too that made Mr. Greene once insist that a dentist extract a healthy tooth because he so wanted the ether that was used.

from profile of Graham Greene by Gloria Emerson, March 1978, Rolling Stone