
Euclid's Elements
Five assumptions about points and lines, and from them Euclid derives hundreds of theorems, up to the proof that the primes never run out. You finish knowing what a proof is.

Five assumptions about points and lines, and from them Euclid derives hundreds of theorems, up to the proof that the primes never run out. You finish knowing what a proof is.

Zhuang Zhou dreams he is a butterfly and wakes unsure which one is dreaming. The jokes, tall tales, and arguments with logicians that follow work to loosen your grip on your own categories.

Seeing a child about to fall into a well, anyone feels alarm before thinking. Human nature is therefore good, Mencius argues, and a ruler who starves his people forfeits the throne.

Pleasure is the absence of pain and fear, Epicurus taught, so want less and eat plainly. Death is nothing to us: where death is, we are not. Friendship he counted the greatest good.

Confucius answers his students in short exchanges: never do to others what you would not want done to yourself, and let ritual shape everything. Chinese officials memorized it to hold office until 1905.