My experience has shown that many people find it hard to make their design ideas precise. They are willing to express their ideas in loose, general terms, but are unwilling to express them with the precision needed to make them into patterns. Above all, they are unwilling to express them as abstract spatial relations among well-defined spatial parts. I have also found that people aren't always very good at it; it is hard to do..... If you can't draw a diagram of it, it isn't a pattern. If you think you have a pattern, you must be able to draw a diagram of it. This is a crude, but vital rule. A pattern defines a field of spatial relations, and it must always be possible to draw a diagram for every pattern. In the diagram, each part will appear as a labeled or colored zone, and the layout of the parts expresses the relation which the pattern specifies. If you can't draw it, it isn't a pattern.
Christopher Alexander (1979) in The Timeless Way of Building.