Let’s hope that no system of theory of systems will ever eliminate the other systems – that no approach will be promoted to a dogma, and no group of … - Gerald Weinberg

Science is the study of those things that can be reduced to the study of other things.

We were doing incremental development as early as 1957, in Los Angeles, under the direction of Bernie Dimsdale [at IBM's ServiceBureau Corporation]. He was a colleague of John von Neumann, so perhaps he learned it there, or assumed it as totally natural. I do remember Herb Jacobs (primarily, though we all participated) developing a large simulation for Motorola, where the technique used was, as far as I can tell, indistinguishable from XP.

The principle is simple and powerful enough to be Marvin's Fourth Great Secret: If what they've been doing hasn't solved the problem, tell them to do something else.