Yōko Ogawa, Revenge

"For a torture to be effective, the pain has to be spread out; it has to come at regular intervals, with no end in sight. The water falls , drop after drop after drop, like the second hand of a watch, carving up time. The shock of each individual drop is insignificant, but the sensation is impossible to ignore. At first, one might manage to think about other things, but after five hours, after ten hours, it becomes unendurable. The repeated stimulation excites the nerves to a point where they literally explode, and every sensation in the body is absorbed into that one spot on the forehead---indeed, you come to feel that you are nothing but a forehead, into which a fine needle is being forced millimeter by millimeter. You can’t sleep or even speak, hypnotized by a suffering that is greater than any mere pain. In general, the victim goes mad before a day has passed."