In programming, it’s often the buts in the specification that kill you.

Bugs lurk in corners and congregate at boundaries.

A design remedy that prevents bugs is always preferable to a test method that discovers them.

Second law: The complexity barrier. Software complexity (and therefore that of bugs) grows to the limits of our ability to manage that complexity.

If the objective of testing were to prove that a program is free of bugs, then not only would testing be practically impossible, but it would also be theoretically impossible.

Extra features were once considered desirable. We now recognize that 'free' features are rarely free. Any increase in generality that does not contribute to reliability, modularity, maintainability, and robustness should be suspected.

Testing proves a programmer’s failure. Debugging is the programmer’s vindication.