Designers don't design toasters; they design ways to make toast.

• A toaster is only one way to make toast. Different ways to make toast will suit different situations.
• The designer's job is to assess the situation before deciding what intervention is appropriate.
• See also Don Norman's excellent essay, "A Product is More Than the Product".

The largest must fit, and the smallest must reach.

The customer is always wrong.

• The customer doesn't know what they want because they haven't designed whatever they think they want.
• The customer is, however, an expert in what's wrong with the current situation.