“Observe, first, that overall symmetry in a system, by itself, is not a strong source of life or wholeness.”Christopher Alexander, p. 186, Book One, The Nature of Order
“…the Alhambra…a marvel of living wholeness. It has no overall symmetry at all, but an amazing number of minor symmetries, which hold within limited pieces of the design, leaving the whole to be organic, flexible, adapted to the site.”Christopher Alexander, p. 187, Book One, The Nature of Order
What holds space together? What makes it memorable? Often, these two questions are considered to dwell in separate realms of thought, not so in the mind of Christopher Alexander. Throughout nature and in the very best architecture, an interwoven field of local symmetries is often pervasive. On the other hand, a global symmetry of the kind found in certain neoclassical buildings or in structures produced by top down organizations like the Pentagon produce a deadly, mind numbing kind of order. Often, globally symmetric structures are produced at the cost of neutralizing the natural asymmetry of existing conditions. Rather than holding space together, global symmetry tends to create a separation between itself and everything else.
Local symmetry is the result of a bond of sorts, a geometrical relationship between two or more related parts or centers, as Alexander is apt to say. Nature is replete with this geometry, often the result of the act of an incremental symmetrical cell division process known as morphogenesis. Apparently, humans resonate with and more easily remember the density of overlapping local symmetries even though they may be unaware of their presence. This effect was illustrated in an experiment conducted by Alexander while working at the Harvard Center for Cognitive Studies. In 1971, when, as an architecture student, I visited the Alhambra in Granada Spain, little did I know that my utter wonderment of the place had mostly to do with how it manifested local symmetries.