The analysis model will not be a reflection of what the problem domain looks like... The reason is simply to get a more maintainable structure where changes will be local and thus manageable. We thus do not model reality as it is, as object orientation is often said to do, but we model the reality as we want to see it and to highlight what is important in our application.

p. 185: cited in: "Object Oriented Software Engineering: A Use Case Driven Approach Ivar Jacobson, et al. (1992)", Book review by Ted Felix on tedfelix.com, 2006. - Object-Oriented Software Engineering: A Use Case Driven Approach (1992)