Three and a half million years ago our ancestors - yours and mine - left these traces [indicates footprints]. We stood up and parted ways from them. Once we were standing on two feet, our eyes were no longer fixated on the ground. Now, we were free to look up and wonder.

You have the illusion of free will, but, in fact, that illusion comes about because you don't know the future. Because you are a prisoner of the present, forever locked in transition, between the past and the future.

So much of what we understand comes from knowing what something is and what that something used to be, which allows us to figure out, or at least imagine, what happened in between.

For me, I am driven by two main philosophies, know more today about the world than I knew yesterday. And along the way, lessen the suffering of others. You'd be surprised how far that gets you.

Science is not there for you to cherry pick ... You can decide whether or not to believe in it but that doesn’t change the reality of an emergent scientific truth.

But to measure cause and effect... you must ensure that a simple correlation, however tempting it may be, is not mistaken for a cause. In the 1990s the stork population of Germany increased and the German at-home birth rate rose as well. Shall we credit storks for airlifting the babies?

During the 1970s and 1980s, the popular television soap opera As The World Turns portrayed sunrise during the opening credits and sunset during the closing credits... The soap-opera sunrise showed the sun moving toward the left as it rose rather than to the right. They obviously had gotten a piece of film showing a sunset and played it in reverse... Had they called their local astrophysicists, any one of us might have recommended that if they needed to save money, they could have shown the sunset in a mirror before they showed it running backward.