The practical function of language is to let us describe facts and prescribe acts, to make statements and issue commands. The use of language for these purposes, inevitably affects our empirical and normative experience, our sense of what is real and ideal, what is and what should be. Language shapes our imaginations.
The "language arts," philosophy and poetry perhaps most clearly, work upon our imaginations deliberately. Their aim is to improve the accuracy of imagination, our sense of what is possible. They also try to move us to recognize certain necessities.
I say "the arts" here, and I impute a will to them, an intention, because I do not think the immediate aim of artists is always this. It's just that when they succeed, when they produce "a work of art," it is because what they have done, for whatever petty goals they may themselves have pursued, is to help us better imagine the facts and acts before us.
We become better able to see what must be, and do what we can.