Northrop Frye, from The Educated Imagination (1962):

So you may ask, what is the use of studying a world of imagination where anything is possible and anything can be assumed, where there are no rights or wrongs and all arguments are equally good? One of the most obvious uses, I think, is its encouragement of tolerance. In the imagination our own beliefs are also only possibilities, but we can also see the possibilities in the beliefs of others. Bigots and fanatics seldom have any use for the arts, because they’re so preoccupied with their beliefs and actions that they can’t see them as also possibilities. It’s possible to go the other extreme, to be a dilettante so bemused by possibilities that one has no convictions or power to act at all. But such people are much less common than bigots, and in our world much less dangerous.

What produces the tolerance is the power of detachment in the imagination, where things are removed just out of reach of belief and action. Experience is nearly always commonplace; the present is not romantic in the way that the past is, and ideals and great visions have a way of becoming shoddy and squalid in practical life. Literature reverses this process. When experience is removed from us a bit, as the experience of the Napoleonic was is in Tolstoy’s War and Peace, there’s a tremendous increase of dignity and exhilaration. I mention Tolstoy because he’d be the last writer to try and glamorize the war itself, or pretend that its horror wasn’t horrible. There is an element of illusion even in War and Peace, but the illusion gives us a reality that isn’t in the actual experience of the war itself: the reality of proportion and perspective, of seeing what it’s all about, that only detachment can give. Literature helps to give us that detachment, and so do history and philosophy and science and everything else worth studying. But literature has something more to give peculiarly its own: something as absurd and impossible as the primitive magic is so closely resembles.