The 15 Properties of Living Structures

The following text is written by Règis Medina:

Alexander has studied extensively what properties were exhibited by living structures. He compared hundreds, maybe thousands of structures, trying to understand each time what living structures had that lifeless ones had not.

Over time, he came up with a list of 15 properties. These properties are different kind of relationships between centers that help create a living structure. The more the centers of a given design reinforce themselves through these 15 properties, the more life the structure will have.

These properties are the following:

• Levels of scale
• Strong centers
• Boundaries
• Alternating repetition
• Positive space
• Good shape
• Local Symmetries
• Deep interlock & ambiguity
• Contrast
• Gradients
• Roughness
• Echoes
• The Void
• Simplicity and Inner Calm
• Not-separateness

I will only present a few of them here, in particular those that I find relevant to the field of software. For a complete description, there's probably no substitute for a thorough reading of tome 1 of The Nature of Order: The Phenomenon of Life. You will find there dozens and dozens of pictures that illustrate them in great detail.

In the meantime, here is a quick overview of some of them:

Photo: B_cool

This tiger face is filled with centers. The eyes and the nose are the Strong Centers of this face. There are many Local Symmetries, starting with that of the whole face. There are Boundaries around the eyes or the nose. There is Contrast in the black and white colors of the fur around the eyes or the nose. There is Alternating Repetition of the stripes. There is Roughness in the fact that the stripes are not perfectly regular or symmetrical.