Among people I have met, the few whom I would term “great” all share a kind of unquestioned, fierce dedication; an utter lack of doubt about the value of their activities (or at least an internal impulse that drives through any such angst); and above all, a capacity to work (or at least to be mentally alert for unexpected insights) at every available moment of every day of their lives.

People are clever, but almost no one ever devises an optimal quip precisely at the needed moment. Therefore, virtually all great one-liners are later inventions - words that people wished they had spouted, but failed to manufacture at the truly opportune instant.

The proof of evolution lies in those adaptations that arise from improbable foundations.

The center of human nature is rooted in ten thousand ordinary acts of kindness that define our days.

Forelimbs of people, porpoises, bats and horses provide the classic example of homology in most textbooks. They look different, and do different things, but are built of the same bones. No engineer, starting from scratch each time, would have built such disparate structures from the same parts.

World views are social constructions and they channel the search for facts. But facts are found and knowledge progresses, however fitfully.

Heydrich, Eichmann, and company therefore invoke the usual trick of argument for breaking a true continuum that lacks a compelling point for separation: choose an arbitrary dividing line and then treat it as a self-evident law of nature.