Thinking clearly

One idea from each of the 14 books on this topic.

• Never go to war just because you are angry. Anger may in time change to gladness; vexation may be succeeded by content. But a kingdom that has once been destroyed can never come again into being.

  From The Art of War by Sun Tzu

• Why not leave Athens and keep quiet? Because talking every day about how to live is the greatest good a person has, and “the unexamined life is not worth living”. He knew the jury would find that the hardest part to believe.

  From The Trial and Death of Socrates by Plato

• A rule about who gets served first, who speaks first, who bows to whom, looks like pure decoration from the outside. It’s closer to traffic control. Remove the traffic lights and the wanting underneath doesn’t go away, it just collides at the intersection.

  From Xunzi by Xunzi

• Plato defined a human being as a two-footed animal without feathers. Diogenes plucked a chicken, carried it into the school, and said, “This is Plato’s man.”

  From Lives of the Eminent Philosophers by Diogenes Laertius

• Most of your troubles don’t come from nature or from other people. They come from your own excess. Wanting silver dishes leads to wanting gold ones, then sapphire, and that wanting never ends.

  From Guide for the Perplexed by Moses Maimonides

• Sorrow has plain remedies. Any pleasure eases it, and so do tears and the sympathy of friends, who seem to share the weight. Looking at a truth helps. So do sleep and baths, because whatever sets the body right again eases the mind.

  From Summa Theologica by Thomas Aquinas

• When you buy a horse, you strip off the saddle and look at the legs. Judge a person the same way, without money, titles or fine clothes. “Measure him without his stilts,” then ask what kind of mind is left.

  From Essays by Michel de Montaigne

• Some of what you believe is false, and you can’t tell which part. You took most of it on as a child, long before you could check it. Testing each belief would never end. Test the foundations instead, because everything else was built on them.

  From Meditations on First Philosophy by René Descartes

• People go to sea, go to war, and gamble their money away for one reason: they cannot stay quietly in their own chamber. Sitting still with nothing to do, you start to feel how weak and mortal you are. The busyness is there to keep that thought away.

  From Pensées by Blaise Pascal

• A stone falls from a roof and kills a man, and someone says God meant it. Answer with the wind and his errand, and they ask why the wind blew just then. The questions go back until you take refuge in the will of God, the sanctuary of ignorance.

  From Ethics by Baruch Spinoza

• People complain about their memory all the time and almost never about their judgment. A bad memory is easy to admit because it says little about you. Bad judgment says a lot.

  From Maxims by François de La Rochefoucauld

• Bread has fed you every time you ate it, so you expect the next loaf to feed you too. No argument gets you from past to future, since every argument from experience already assumes the future will match the past. That’s reasoning in a circle.

  From An Enquiry Concerning Human Understanding by David Hume

• Some errors stay after you spot them. The rising moon looks bigger even to an astronomer who knows better. Reason’s pull past experience stays too.

  From Critique of Pure Reason by Immanuel Kant

• To shut someone up is to act as if you can’t be wrong. Everyone admits they make mistakes, but almost nobody applies that to the beliefs their own circle shares. The chance that made you a churchgoer in London would have made you a Buddhist or a Confucian in Beijing.

  From On Liberty by John Stuart Mill