I went back to this recently, to get my head back in the right groove when working out how to model complex relationship structures. It still makes me gasp.

RUDI: Bookshelf: Classics: Christopher Alexander: A city is not a tree part 1

Here’s how it ends:

For the human mind, the tree is the easiest vehicle for complex thoughts. But the city is not, cannot and must not be a tree. The city is a receptacle for life. If the receptacle severs the overlap of the strands of life within it, because it is a tree, it will be like a bowl full of razor blades on edge, ready to cut up whatever is entrusted to it. In such a receptacle life will be cut to pieces. If we make cities which are trees, they will cut our life within to pieces.