The only limit is the one you set for yourself.

Algebraic geometry is the study of zeros of polynomials.

It seems to me that the natural world is the greatest source of excitement; the greatest source of visual beauty; the greatest source of intellectual interest. It is the greatest source of so much in life that makes life worth living.

The other thing about modern society and why it causes this anxiety, is that we have nothing at its center that is non-human. We are the first society to be living in a world where we don't worship anything other than ourselves. We think very highly of ourselves, and so we should; we've put people on the Moon, done all sorts of extraordinary things. And so we tend to worship ourselves.