In the 1970s, many intellectuals had become political radicals. Marxism was correct, liberalism was for wimps, and Marx had pronounced that 'the ruling ideas of each age have ever been the ideas of its ruling class.'

No matter how inured you get to atrocities, you're still always stunned and shocked by how cruel and wasteful Homo sapiens can be.

I think that metaphor really is a key to explaining thought and language. The human mind comes equipped with an ability to penetrate the cladding of sensory appearance and discern the abstract construction underneath - not always on demand, and not infallibly, but often enough and insightfully enough to shape the human condition. Our powers of analogy allow us to apply ancient neural structures to newfound subject matter, to discover hidden laws and systems in nature, and not least, to amplify the expressive power of language itself.

Pre-state societies were far more violent than our own.

Of course genes can’t pull the levers of our behavior directly. But they affect the wiring and workings of the brain, and the brain is the seat of our drives, temperaments and patterns of thought. Each of us is dealt a unique hand of tastes and aptitudes, like curiosity, ambition, empathy, a thirst for novelty or for security, a comfort level with the social or the mechanical or the abstract. Some opportunities we come across click with our constitutions and set us along a path in life.

Nature is a hanging judge," goes an old saying. Many tragedies come from our physical and cognitive makeup. Our bodies are extraordinarily improbable arrangements of matter, with many ways for things to go wrong and only a few ways for things to go right. We are certain to die, and smart enough to know it. Our minds are adapted to a world that no longer exists, prone to misunderstandings correctable only by arduous education, and condemned to perplexity about the deepest questions we can ascertain.

The Rights Revolutions too have given us ideals that educated people today take for granted but that are virtually unprecedented in human history, such as that people of all races and creeds have equal rights, that women should be free from all forms of coercion, that children should never, ever be spanked, that students should be protected from bullying, and that there’s nothing wrong with being gay. I don’t find it at all implausible that these are gifts, in part, of a refined and widening application of reason.