Time

If you are unfamiliar with Goldsworthy, go Google him now! He's an artist and photographer and most of his art is only around for as long as it takes Nature to do away with it, so the photos are all that endures. He has a number of books published that feature his art, but this is my favorite of the ones I've seen. Goldsworthy allows you to see your environment in totally new, unpredictable ways that actually make you appreciate your surroundings more.