Chapter 7. Patterns and System Development

When a person is faced with an act of design, what he does is governed entirely by the pattern language which he has in his mind at that moment. Of course, the pattern languages in each mind are evolving all the time, as each person's experience grows. But at the particular moment he has to make a design, he relies entirely on the pattern language he happens to have accumulated up until that moment. His act of design, whether humble or gigantically complex, is governed entirely by the patterns he has in his mind at that moment, and his ability to combine these patterns to form a new design.

—Alexander, 79