Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.

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

If you're as clever as you can be when you write it, how will you ever debug it?

Get the weirdnesses into the data where you can manipulate them easily, and the regularity into the code because regular code is a lot easier to work with

Don't document bad code - rewrite it.

Controlling complexity is the essence of computer programming.

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