Software is usually expected to be modified over the course of its productive life. The process of converting one correct program into a different correct program is extremely challenging.
Douglas Crockford (2008). “JavaScript: The Good Parts: The Good Parts”, p.94, "O'Reilly Media, Inc."
![Software is usually expected to be modified over the course of its productive life. The process of converting one correct program into a different correct program is extremely challenging.](http://cdn.quoteddaily.com/images/douglas-crockford/software-is-usually-expected-to-be-modified-over-the-course-of-its-productive-life-the-process-of-converting-one-correct.jpg)