What is the theme in A Severed Head by Iris Murdoch?

Insanity is another theme in the book. It is perhaps meant to be ironic that there is a great deal of erratic and insane behavior given the fact that Palmer is a psychoanalyst. The story starts out normally enough. The first big shock is when Martin learns that Antonia is having an affair with Palmer, his best friend. This is where the behavior starts to become slightly strange.