In the late 1970s, Christopher Alexander became an icon in the architecture world with his book, A Pattern Language. In it, he argued for injecting personal, emotional and spiritual qualities into manmade structures, streets and cities. Alexander's book challenged the architectural establishment and derided much that's been built over the past century as "deadly." 

Now, Alexander has issued the final volume of his four-volume tome, The Nature of Order: An Essay on the Art of Building and the Nature of the Universe, which expands on his basic question: how do we build places and structures that are filled with life? Theorizing that order is inherent in both nature and manmade spaces, Alexander attempts to define and understand the essence of a "living" structure. He talks with NPR's Jennifer Ludden.