Happiness is a matter of one’s most ordinary everyday mode of consciousness being busy and lively and unconcerned with self. To be damned is for one’s ordinary everyday mode of consciousness to be unremitting agonising preoccupation with self.The Nice and the Good (1968)
I doubt that the description of damnation given by Willie in The Nice and the Good owes anything to that given by CS Lewis in The Great Divorce, but they agree surprisingly well. Lewis’ version of Hell is of an extreme social distancing, of each damned soul retreating from the others to focus on themselves, how they were wronged, how they were misunderstood.
This, of course, is not a state that requires an after-life to experience. Willie is saying that the difference between damnation and happiness (in the normal run of things) is purely a matter of where attention is directed: internally or externally. As Murdoch pointed out in her philosophical essay “The Sublime and the Good” (1959, Chicago Review, Vol. 13 Issue 3), “love, and so art and morals, is the discovery of reality”: the recognition of the entire world, not just what is inside ones own head.