Watch this video by by Stuart Anstis from the University of California, San Diego, and Clara Casco from the University of Padua, Italy, and note the motion of the two flies. Then read an explanation of the two flies in the New Scientist:

Whether you are designing an FM radio, an editorial product, or a software product, good design is largely about about making things clear and understandable. It's about sharp priorities and radical simplifications that reveal shocking truths: you don't need sixteen controls when one will suffice.

Steve Jobs was a performer. When I worked at a university, I remember being called over to Alex Kluge's desk: "Steve Jobs is going to be streaming in a few minutes. Alex has it set up." This was back in the late 1990's when Apple was struggling, and it was not clear how they'd make it. We gathered around the largest monitor I had ever seen. Alex made sure the video was working, then he went full-screen. We all stared and saw Steve deliver something so advanced, so unexpectedly lovely that I heard some engineers and professors swearing and cussing, and saw them squint in disbelief.