Why did his interest in the concept of spontaneous order and the history of the doctrine of unintended social consequences undergo very little development after the 1960s? All of his political writings are in fact amazingly repetitious, exploring a small number of big themes which, however, are not further refined or extended in new contexts. As organizing concepts, they held, I am convinced, enormous potentialities but nevertheless Hayek himself failed to realize them.

Hayek revisited (1993)