Testing is not the point. The point is about responsibility.

Learning research tells us that the time lag from experiment to feedback is critical.

The system metaphor is a story that everyone--customers, programmers, and managers--can tell about how the system works.

Code wants to be simple... I had to give up the idea that I had the perfect vision of the system to which the system had to conform. Instead, I had to accept that I was only the vehicle for the system expressing its own desire for simplicity. My vision could shape initial direction, and my attention to the desires of the code could affect how quickly and how well the system found its desired shape, but the system is riding me much more than I am riding the system.

Make it work, make it right, make it fast.

I've known people who have not mastered their tools who are good programmers, but not a tool master who remained a mediocre programmer.

If you're having trouble succeeding, fail.