" Julia used to say, 'Poor Sebastian. It's something chemical in him.' That was the cant phrase of the time, derived from heaven knows what misconception of popular science. 'There's something chemical between them' was used to explain the overmastering hate or love of any two people. It was the old concept of determinism in a new form. I do not believe there was anything chemical in my friend. "
― Evelyn Waugh , Brideshead Revisited