Ask not first what the system does; ask what it does it to!

Constants are widely known for the detestable practice of changing their values; we should prepare ourselves against the consequences of such fickleness

I have always felt sympathy towards the biologists who accept to debate creationists. Now I also understand them better; one can fight opinions, not articles of faith.

I think Smalltalk is inappropriate for serious industrial developments. After all, run time is a little late to find out whether you have a landing gear.

Perfect reusable components are not obtained at the first shot.

Software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification.

Incorrect documentation is often worse than no documentation.