It was about people whose mental diseases couldn't be treated because the causes of the diseases were all in the fourth dimension, and three-dimensional Earthling doctors couldn't see those causes at all, or even imagine them. One thing Trout said that Rosewater liked very much was that there really were vampires and werewolves and goblins and angels and so on, but that they were in the fourth dimension. So was William Blake, Rosewater's favorite poet, according to Trout. So were heaven and hell.