Which is harder to change: a program with 1000 lines of code or a 1000 square foot slab of concrete?

Believe me, it's easier to break concrete than to change code. It's like that 70's riddle: How many Californians does it take to change a lightbulb? Just one, but the bulb has to want to change! We are dealing with more than just the physical world here. We have to deal with the programmer's mind-a much more resistant material than mere steel-reinforced concrete.(alan cooper, the perils of prototyping, 1994)

nice 'historical' text (talking about visual basic and hypercard) about prototyping, programmers and code.