The other is a disease

This distinction holds for adult reading too. The dangerous fantasy is always superficially realistic. The real victim of wishful reverie does not batten on the Odyssey, The Tempest, or The Worm Ouroboros: he (or she) prefers stories about millionaires, irresistible beauties, posh hotels, palm beaches and bedroom scenes—things that really might happen, that ought to happen, that would have happened if the reader had had a fair chance. For, as I say, there are two kinds of longing. The one is an askesis, a spiritual exercise, and the other is a disease.

~ C. S. Lewis, from Maria Papova’s C.S. Lewis on the Three Ways of Writing for Children and the Key to Authenticity in All Writing