Architect, scientist, and writer Christopher Alexander is one of the most remarkable thinkers and makers of our time. His many books include A Pattern Language (1977), The Timeless Way of Building (1979), and A Foreshadowing of Twenty-First Century Art: The Color and Geometry of Very Early Turkish Carpets (1993). This essay is his recent effort to distill the major discoveries in his masterful four-volume The Nature of Order (2002-2005), published by the Center for Environmental Structure in Berkeley, CA. He wishes to thank Maggie Alexander and Randy Schmidt for help in editing this essay. © 2007 Christopher Alexander. www.patternlanguage.com.