This is an excerpt from Christopher Alexander's Nature of Order, volume 2, The Process of Creating Life:

Perhaps a glossary is in order:

The usage in the text is somewhat ambiguous. Sometimes it means an entire building site, sometimes a feeling, sometimes a notion of ontological everything-ness. It is both a whole thing, and the state of being whole. Contrast with an analytical decomposition.
This is a broader definition than just biological life. We can imagine it like an ecological relationship between biological life and an arrangement of space that engenders, promotes and enhances biological life.
A center is a perceptible region in space, differentiated by some kind of contrast: mass, shape, pigment, etc. It may or may not have a solid boundary, but you should be able to point to it.
Fifteen properties
Alexander has distilled an essential catalogue of 15 geometric and/or physical properties that he believes combine to create living structure.
Structure-preserving transformation
This is an analogous process that generates one of the fifteen properties into a region of space.
Living structure
Living structure is that which promotes life, as defined herein. It exhibits the fifteen properties in abundance, and is built using structure-preserving transformations.

The Fundamental Differentiating Process

  1. At any given moment in a process, we have a certain partially evolved state of a structure. This state is described by the wholeness: the system of centers, and their relative nesting and degrees of life.
  2. We pay attention as profoundly as possible to this wholeness—its global, large-scale order, both actual and latent.
  3. We try to identify the sense in which this structure is weakest as a whole, weakest in its coherence as a whole, most deeply lacking in feeling.
  4. We look for the latent centers in the whole. These are not those centers which are robust and exist strongly already; rather, they are centers which are dimly present in a weak form, but which seem to us to contribute to or cause the current absence of life in the whole.
  5. We then choose one of these latent centers to work on. It may be a large center, or middle-sized, or small.
  6. We use one or more of the fifteen structure-preserving transformations, singly or in combination, to differentiate and strengthen the structure in its wholeness.
  7. As a result of the differentiation which occurs, new centers are born. The extent of the fifteen properties which accompany creation of new centers will also take place.
  8. In particular we shall have increased the strength of certain larger centers; we shall also have increased the strength of parallel centers; and we shall also have increased the strength of smaller centers. As a whole, the structure will now, as a result of this differentiation, be stronger and have more coherence and definition as a living structure.
  9. We test to make sure that this is actually so, and that the presumed increase of life has actually taken place.
  10. We also test that what we have done is the simplest differentiation possible, to accomplish this goal in respect of the center that is under development.
  11. When complete, we go back to the beginning of the cycle, and apply the same process again.