"Ah Humboldt had been great – handsome, high-spirited, buoyant, ingenious, electrical, noble. To be with him made you feel the sweetness of life. [...]. To talk to him was sustaining, nourishing. But I used to think, when he mentioned people who had been his friends, that it could be only a question of time before I too was dropped. He had no old friends, only ex-friends. He could become terrible, going into reverse without warning. When this happened, it was like being caught in a tunnel by the Express. You could only cling to the walls, or lie between the rails, praying."
Saul Bellow (1915-2005). Humboldt's Gift (1975). London: Penguin Books, 2008, p. 164