“Darwin was like a salesman who finds lots of little ways to get you to say yes before you’re asked to utter the big yes. He invited people to affirm things they already knew, about a topic much more familiar in their era than in ours: domestic species.

It only took a couple of years for Darwin to formulate the idea of evolution by natural selection. It took thirty years to frame that idea in a way that would convince other scientists and the general public.