Ivar Jacobson quotes

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. (Ivar Jacobson)
People regard their environment in terms of objects. Therefore it is simple to think in the same way when it comes to designing a model. View quote
Ivar Jacobson
A use case is a complete course of events in the system, seen from a user's perspective. View quote
Ivar Jacobson
When a user uses the system, she or he will perform a behaviorally related sequence of transactions in a dialogue with the system. We call such a special sequence a use case. View quote
Ivar Jacobson
The control objects model functionality that is not naturally tied to any other object... We do not believe that the best (most stable) systems are built by only using objects that correspond to real-life entities, something that many other object-oriented analysis and design techniques claim... Behavior that we place in control objects will, in other methods, be distributed over several other objects, making it hard to change this behavior. View quote
Ivar Jacobson