Our thoughts are shackled by the familiar. The brain is a neural tangle of near infinite possibility, which means that it spends a lot of time and energy choosing what not to notice. As a result, creativity is traded away for efficiency; we think in literal prose, not symbolist poetry.
A bit of distance, however, helps loosen the chains of cognition, making it easier to see something new in the old; the mundane is grasped from a slightly more abstract perspective. As T. S. Eliot wrote in the Four Quartets: "We shall not cease from exploration, and the end of all our exploring will be to arrive where we started and know the place for the first time."
We travel because we need to, because distance and difference are the secret tonic of creativity. When we get home, home is still the same. But something in our mind has been changed, and that changes everything.
Tremendous good read from Jonah Lehrer on why travel is good for the brain.
Also appears in the latest McSweeney's Reader. Found via the AFAR blog.