Physicists are atoms' way of thinking about atoms.

What this means in practice is that if you are not a born worrier you have nothing to worry about (though of course you wouldn't be worrying anyway), whereas if you are a worrier by nature there is absolutely nothing you can do about it, so you may as well stop worrying, except of course you can't.

There is always a little more toothpaste in the tube. Think about it.

I love the feeling of being anonymous in a city I've never been before.

I can't fix the world. If you want to make a difference in life, you have to direct your energies in a focused way.

I can wear a baseball cap; I am entitled to wear a baseball cap. I am genetically pre-disposed to wear a baseball cap, whereas most English people look wrong in a baseball cap.

The number of people on whose cooperative efforts your eventual existence depends has risen to approximately 1,000,000,000,000,000,000, which is several thousand times the total number of people who have ever lived.