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

How good the design is doesn't matter near as much as whether the design is getting better or worse. If it is getting better, day by day, I can live with it forever. If it is getting worse, I will die.

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

Sometimes the problem has to mature before the solution can mature.

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

Of the four project development variables - scope, cost, time and quality - quality isn't really a free variable. The only possible values are excellent and insanely excellent, depending on whether lives are at stake.

If you're having trouble succeeding, fail.

A plan is an example of what could happen, not a prediction of what will happen.

The business changes. The technology changes. The team changes. The team members change. The problem isn't change, per se, because change is going to happen the problem, rather, is the inability to cope with change when it comes.

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

Responsible Development shares many practices with XP but the roots are different. Responsible Development's values are honesty, transparency, accountability and responsibility. These lead me to pairing, test-first, incremental design, continuous integration and so on because they support the values.

I mean, source code in files how quaint, how seventies!