What is a pattern? (one)
“They are not abstract principles that require you to rediscover how to apply them successfully, nor are they overly specific to one particular situation or culture. Instead, they are somewhere in between: a pattern describes possible good solutions to a common design problem within a certain context, by describing the invariant qualities of all those solutions.” Tidwell
“Each pattern describes a problem which occurs over and over again … and then describes the core of the solution to that problem” Alexander