Reality is merely an illusion, albeit a very persistent one.
Planning for change is a principle based on the underlying premise that it is impossible to precisely specify or control all requirements for an integrated enterprise information system. As this quote from Einstein suggests, when we think we have a clear specification for an application interface, it may not be reality. Factors that contribute to the hopelessness of realizing precise and complete specifications include
• Unpredictability of complex dependent software systems with millions of permutations and combinations of internal states
• Constantly evolving needs because of business, market, or technology changes ...