The reason we wouldn't make a seven-inch tablet isn't because we don't want to hit a price point, it's because we don't think you can make a great tablet with a seven-inch screen.

It takes these very simple-minded instructions - 'Go fetch a number, add it to this number, put the result there, perceive if it's greater than this other number' - but executes them at a rate of, let's say, 1,000,000 per second. At 1,000,000 per second, the results appear to be magic.

The journey is the reward

Most people have no concept of how an automatic transmission works, yet they know how to drive a car. You don't have to study physics to understand the laws of motion to drive a car. You don't have to understand any of this stuff to use Macintosh.

When you start looking at a problem and it seems really simple, you don't really understand the complexity of the problem. Then you get into the problem, and you see that it's really complicated, and you come up with all these convoluted solutions. That's sort of the middle, and that's where most people stop... But the really great person will keep on going and find the key, the underlying principle of the problem - and come up with an elegant, really beautiful solution that works.

I have a great respect for incremental improvement, and I've done that sort of thing in my life, but I've always been attracted to the more revolutionary changes. I don't know why. Because they're harder. They're much more stressful emotionally. And you usually go through a period where everybody tells you that you've completely failed.

For the past 33 years, I have looked in the mirror every morning and asked myself: 'If today were the last day of my life, would I want to do what I am about to do today?' And whenever the answer has been 'No' for too many days in a row, I know I need to change something.