I have a personal philosophy in life: If somebody else can do something that I'm doing, they should do it. And what I want to do is find things that would represent a unique contribution to the world-the contribution that only I, and my portfolio of talents, can make happen. Those are my priorities in life.

We only recently figured out the origin of our own moon. And we have some idea of how the Sun and Earth formed, but that's only because modern telescopes empower us to see other stars and planets freshly hatched within gas clouds across the galaxy. As for the origin of life itself, the transition from inanimate molecules to what any of us would call life remains one of the great frontiers of biology.

As areas of knowledge grow, so too do the perimeters of ignorance.

Doing what has never been done before is intellectually seductive, whether or not we deem it practical.

Some claim evolution is just a theory. As if it were merely an opinion. The theory of evolution, like the theory of gravity, is a scientific fact. Evolution really happened. Accepting our kinship with all life on Earth is not only solid science. In my view, it’s also a soaring spiritual experience.

Anyone who has wrestled knows that it's the hardest thing in the world to do. Anyone who says something else is the hardest thing has never wrestled. That's what I have found. ... You don't wrestle because it's easy, you wrestle because it's hard. I don't do astrophysics because it's easy, I do it because it's hard. And I juxtapose the two in my mind, body, and soul all the time.

No doubt, the most challenging class of questions in science is the origin of things.