The software technology of that time was concerned primarily with functional correctness and did not pay much attention to the temporal dimension of program execution, which is as important as functional correctness when a physical process must be controlled. In the ensuing years, many problems in the design of cyber- physical systems were simplified. But with an increase in the functional requirements and system size, the complexity problems have appeared again in a different disguise. A sound understanding of the complexity problem requires some insight in cognition, human problem solving, psychology, and parts of philosophy. This book presents the essence of the author¿s thinking about complexity, accumulated over the past forty years.