His essays are rather insightful, and they are available for free on his site. The above mentioned "Where to stand and where to put the edges" is truly an excellent read. I also enjoyed his take on the use of a 35mm camera, it helped to play a part in my own explorations with a small camera from time to time.
It really is amazing, the simple things we take for granted. If I'm most gratefull for any one thing photography has given me it's the ability to view the world with fresh eyes and to appreciate the visual spledor we're constantly surroded by... I think Mark's photographs exemplify that as much as anyones.