Innocence lost is not easily regained. The designer simply cannot predict the problems people will have, the misinterpretations that will arise, and … - Donald Norman

In their work, designers often become expert with the device they are designing. Users are often expert at the task they are trying to perform with the device. [...] Professional designers are usually aware of the pitfalls. But most design is not done by professional designers, it is done by engineers, programmers, and managers.

The major problems facing the development of products that are safer, less prone to error, and easier to use and understand are not technological: they are social and organizational.

When I use a direct manipulation system—whether for text editing, drawing pictures, or creating and playing games—I do think of myself not as using a computer but as doing the particular task. The computer is, in effect, invisible. The point cannot be overstressed: make the computer system invisible.