““The point is best made by stating that not all systems are requirements-driven, at least, not driven by formal written requirements of the kind we have described so far [Rechtin 97]. As an example: A city is a people-made system, but (with a few notable exceptions) no one actually sits down and writes a set of requirements for a city, and then builds it. Rather, cities evolve over time, starting as small settlements exploiting favorable locations or natural resources, and growing as new facilities are added and more people decide to move in. It is most unlikely that the original settlers on Manhattan Island ever dreamed what their creation would grow into!””
