At issue is not only knowledge of the world but our survival as individuals and as a species. All the basic technologies ever invented by humans to feed and protect themselves depend on a relentless commitment to hard-nosed empiricism: you cannot assume that your arrowheads will pierce the hide of a bison or that your raft will float just because the omens are propitious and you have been given supernatural reassurance that they will. You have to be sure.

The war with Iraq ... had to be one of the greatest non sequiturs in military history. Attacked by a gang composed largely of Islamic militants from Saudi Arabia, the United States countered by invading an unrelated country, and one of the most secular in the Middle East at that.

It's even occurred to me, as a teeny little subversive whisper of a thought, that if we stop mowing the lawn right now, it will probably be a long, long time before the yard gets overrun by lions and snakes.

A child is not a salmon mousse. A child is a temporarily disabled and stunted version of a larger person, whom you will someday know. Your job is to help them overcome the disabilities associated with their size and inexperience so that they get on with being that larger person.

What we need is a tough new kind of feminism with no illusions. Women do not change institutions simply by assimilating into them. We need a feminism that teaches a woman to say no - not just to the date rapist or overly insistent boyfriend but, when necessary, to the military or corporate hierarchy within which she finds herself. We need a kind of feminism that aims not just to assimilate into the institutions that men have created over the centuries, but to infiltrate and subvert them.

Heads of state are notoriously ill prepared for their mature careers; think of Adolf Hitler (landscape painter), Ho Chi Minh (seaman), and our own Ronald Reagan.

There is a vast difference between positive thinking and existential courage.