22 March

At school they teach you Pi is defined as the circumference of a circle, divided by its diameter. And that’s true, but what they don’t explain is - why do two perfectly simple finite lines, with clear beginning and end, divide to produce a number that goes on forever, without ever repeating? It’s why the Greeks called the numbers irrational, they made no sense. It was a real crisis in thought. It still is. It also means most circles you get asked to find the area of, don’t have a fixed area. Even though you can see that clearly they do.