Mark Twain once apologized to a friend for writing a three-page letter because he did not have time to write a one-pager.

Much has been written about GUI design and usability. Even more has been said.

It's easy to go on and on about a topic. However, it's more difficult to express concepts in concise, crisply written phrases and sentences, just as it is more difficult to write tight, elegant code. Perhaps that's why it took me some five years to come up with a set of axioms and corollaries that, IMO, embody the very essence of user-centered design.