Quotes by Donald A. Norman

The designer has an obligation to provide an appropriate conceptual model for the way that the device works. It doesn't have to completely accurate but it has to be sufficiently accurate that it will help in both the learning of the operation and also dealing with novel situations.

After all, if you have the majority of customers, then what you do becomes the standard. Your competitors have little choice but to follow. If you are the leader, then having a nonstandard infrastructure is a bad idea. Ultimately, it leads to extinction.

Beauty and brains, pleasure and usability - they should go hand in hand.