In 2008, touring America to promote The God Delusion, I spoke to a large audience at the University of California at Berkeley. It was a nostalgic visit for me, as I had spent two eventful years there as a young man. Today I stand by everything I said in the lecture.

Why are there two sexes, and how is the balance between the two maintained in evolution? The riddle is one that baffled Chales Darwin. He explicitly left it for later generations. It was eventually solved, with typical brilliance, by the great Ronald Fisher. The fundamental sexual inequality is...

I filmed a conversation about death shortly after Dan Dennett recovered from a life-threatening condition. In addition to discussing personal mortality, we talked about bereavement. I thought this time it would be appropriate to listen again to his wisdom—the wisdom of a great thinker and a dear...