The timeless way of building

is an excellent book by Christopher Alexander (isbn 0-19-502402-8). As usual I'm going to quote from a few pages:
A thing which has the quality without a name never fit any image exactly. What is exact is its adaptation to the forces which are in it.
The fact is that the elements themselves are patterns of relationships.
Any thing which lives can only be achieved as the end product of a process, whose force takes over and replaces the willful act of creation.
The mastery of what is made does not lie in the depths of some impenetrable ego; it lies, instead, in the simple mastery of the steps in the process, and in the definition of those steps.
How does the pattern language, which exists behind this flux, steer it, and enter into it? It hinges on the close relationship between the process of creation and the process of repair.
As in the organism, there is no sharp difference between the process of construction and the process of repair. Each process of construction helps repair some larger whole, of which it is merely a part. No thing is whole unto itself.
Within this process, every individual act of building is a process in which space gets differentiated. It is not a process of addition, in which pre-formed parts are combined to create a whole: but a process of unfolding, like the evolution of an embryo, in which the whole precedes its parts, and actually gives birth to them, by splitting.
The form of the whole, and the parts, come into being simultaneously.
This can only happen if the design is represented in an utterly fluid medium; it cannot happen in any medium where there is even the slightest resistance to change.
No building is ever perfect.