Once I wept for I had no shoes. Then I met a man with no feet, so I took his shoes. I mean, it wasn't as if he was going to need them.

Our population and our use of the finite resources of planet Earth are growing exponentially, along with our technical ability to change the environment for good or ill.

So next time someone complains that you have made a mistake, tell him that may be a good thing. Because without imperfection, neither you nor I would exist.

The universe does not behave according to our pre-conceived ideas. It continues to surprise us.

I want to know why the universe exists, why there is something greater than nothing.

Someone told me that each equation I included in the book would halve the sales.

Why are we here? Where do we come from? Traditionally, these are questions for philosophy, but philosophy is dead.