Imagination is certainly essential to science, applied or pure. Without a constructive power in the mind to make models of experience, get hunches and follow them out, play freely around with hypotheses, and so forth, no scientist could get anywhere. But all imaginative effort in practical fields has to meet the test of practicability, otherwise it’s discarded. The imagination in literature has no such test to meet. You don’t relate it directly to life or reality: you relate works of literature… to each other. Whatever value there is in studying literature, cultural or practical, comes from the total body of our reading, the castle of words we’ve built, and keep adding new wings to all the time. As for us, we can’t even speak of think or comprehend even our own experience except within the limits of our own power over words, and those limits have been established for us by our great writers.
From The Educated Imagination and Other Writings on Critical Theory: 1933-1963 (2006) by literary critic Northrop Frye.