Michael Scammel’s biography runs to 700 pages and is likely to be the primary source on Koestler for some time. A minor quibble, the writing is competent but no more than that, it is a shame that such a fine writer did not get a more than competent biographer.Koestler was larger than life in many ways, as a journalist, a political activist, an on-the-spot observer of some pivotal events the 20th century, a novelist, essayist, manic-depressive, voracious drinker and philanderer, mystic and a serious student of the history of ideas, biology and psychology. If you made up a character like Koestler in a work of fiction the critics would say there was a lack of credibility, like James Bond or Indiana Jones.
He was an outstanding success in many ventures. He became a leading science journalists early in life, he wrote Darkness at Noon, one of the most influential books of the century, he played a leading role in the cultural fightback against the communists. However at the end he suffered huge disappointment when the serious scientific books that he wrote were dismissed by the professionals as lightweight.
From the CR point of view the most interesting feature of his intellectual life is the way he needed CR and classical liberalism, the first to release him from the desperate quest for certainty and the second to provide a political roost after he gave up on communism.
For a younger generation who only know about Koestler as a rumour, I am sorry I can’t summarise the 700 pages but have a look at Wik anyway!