Excerpts from Christopher Alexander One Two Three

The author starts in chapter one by making many analogies to explain that complex things in the world do not just happen. In other words, we cannot suddenly give birth to something gigantic without explanations. Those things can only be generated by a process. After that, the authors talks about buildings and the process of their construction.
He describes in a very interesting and simple way how the process of building is just a collection of patterns that give builders the ability to combine them to create an infinite variety of buildings.

We can clearly see how this applies to software architecture. In architecting a system, the architect uses patterns, which are things that repeat. That is he does not invent or suddenly give birth to the architecture of the system, but uses known best practices and solutions to similar problems as references while building the new architecture. Those known best practices and solutions can be combined and arranged into different ways to form various new architectures. So the architect makes the appropriate use of the patterns to produce the new architecture.

The notion of having a pattern language is also very interesting because we can think of the collection of patterns as a set of words in a language. To support that the author makes the analogy that ordinary languages give us the power to create an infinite variety of sentences. So if we think in theme of software architecture we can say that the pattern language gives architects the power to create a variety of architectures.