"We must not encourage in ourselves or others any tendency to work up a subjective state which, if we succeeded, we should describe as “faith,” with the idea that this will somehow insure the granting of our prayer. We have probably all done this as children. But the state of mind which desperate desire working on a strong imagination can manufacture is not faith in the Christian sense. It is a feat of psychological gymnastics."
C. S. Lewis (via ratchetlyproper