In his "Adagia," Wallace Stevens wrote, "Reality is a cliché from which we escape by metaphor," a statement which has often puzzled (if not troubled) me. Here's what I have come to believe Stevens means.
As Basho suggests, it is an error to isolate the objective from the subjective. The only reality we can ever know is one that includes our presence and which is filtered by our own perceptions, perceptions which are necessarily conditioned by the expectations we bring to them and by the modes of thinking and perceiving that we have already acquired. It is these preconceptions that render our experience of reality a cliché.
Metaphor allows us to break away from this diminished engagement with reality by forcing us to see our world in new ways, in particular by allowing us to see the essential connections between things we previously knew as wholly separate. Metaphor provides a means to escape that trap, but it is not a form of escapism; if anything, metaphor brings us closer to the reality outside our selves by disrupting the internalized categories we inevitably impose upon the world we see.