If you keep cutting, is there an end?

That time, that place

Abdera sat on the coast of Thrace. With his teacher Leucippus, and with no instrument of any kind, Democritus tried to reason his way down to the bottom of matter.

Why this question

It was an experiment run entirely in the mind. Split a stone in half, split the half, keep splitting. Only two roads: either it divides forever, or something turns up that cannot be divided.

Suppose it divides forever. Then at the end nothing is left but things of no size. And no pile of sizeless things can add up to a stone.

What was found

So there must be a grain that cannot be cut. They called it atomos — uncuttable. All that exists is these grains and the empty space between them; sourness and redness are appearances produced by their shapes and arrangements.

There was no evidence whatsoever. It was a conclusion reached by argument alone, and confirming it would take 2,200 years.