Believe the terrain, not the map

C is a razor-sharp tool, with which one can create an elegant and efficient program or a bloody mess.

Controlling complexity is the essence of computer programming.

Don't document bad code - rewrite it.

Another effective [debugging] technique is to explain your code to someone else. This will often cause you to explain the bug to yourself. Sometimes it takes no more than a few sentences, followed by an embarrassed "Never mind, I see what's wrong. Sorry to bother you." This works remarkably well; you can even use non-programmers as listeners. One university computer center kept a teddy bear near the help desk. Students with mysterious bugs were required to explain them to the bear before they could speak to a human counselor.

90% of the functionality delivered now is better than 100% delivered never.

Each new user of a new system uncovers a new class of bugs.