In a version of the class taught last year, Mr. Nelson showed a slide of “The Bull,” a series of 11 lithographs of a bull that Picasso created over about a month, starting in late 1945. In the early stages, the bull has a snout, shoulder shanks and hooves, but over the iterations, those details vanish. The last image is a curvy stick figure that is still unmistakably a bull.

“You go through more iterations until you can simply deliver your message in a very concise way, and that is true to the Apple brand and everything we do,” recalled one person who took the course.

In “What Makes Apple, Apple,” another course that Mr. Nelson occasionally teaches, he showed a slide of the remote control for the Google TV, said an employee who took the class last year. The remote has 78 buttons. Then, the employee said, Mr. Nelson displayed a photo of the Apple TV remote, a thin piece of metal with just three buttons.

How did Apple’s designers decide on three buttons? They started out with an idea, Mr. Nelson explained, and debated until they had just what was needed — a button to play and pause a video, a button to select something to watch, and another to go to the main menu.

The Google TV remote serves as a counterexample; it had so many buttons, Mr. Nelson said, because the individual engineers and designers who worked on the project all got what they wanted. But, Apple’s designers concluded, only three were needed.

Creators need an immediate connection to what they're creating. Creators need to be able to see what they’re doing.

There are millions of ideas locked in millions of heads...all kinds of ideas, including critically important ideas, world changing inventions, life saving scientific discoveries. These are all ideas that must be grown and without an environment in which they can grow, where a creator can nurture them with this immediate connection, many of these ideas will not emerge - or they will emerge stunted. 

When I see a violation of this principle, I don’t think of that as an opportunity. When I see creators constrained by their tools and their ideas compromised, I don’t say, “Oh good, an opportunity to make a product - an opportunity to start a business…” Ideas are very precious to me and when I see ideas dying, it hurts. I see a tragedy. …  And if I think there’s anything I can do about it, I feel it’s my responsibility to do so. Not opportunity, but responsibility.