2. “…to practice in all things a certain sprezzatura [nonchalance], so as to conceal all art and make whatever is done or said appear to be without effort and almost without any thought about it.” Baldassare Castiglione
3. It's how we want technology to work instead of how we don't want it to work.
4. The best applications and interfaces are so simple they "appear to be without effort" and are able to allow users to go about their business "without any thought about it”.