WHEEL

The oldest wheels we can point to come from Mesopotamia. No name on them, no patent, no founder. Somebody cut a disc, punched a hole through the middle, and the rest of us never stopped using it.

The first wheels were not for travel. They spun clay. Potters used them to shape vessels, and those vessels held grain, water and oil — the things a settlement needs to stop moving and start building.

Once the wheel was put on an axle, load stopped being a limit. Sledges became carts. Carts became wagons. One person could move what ten used to drag.

Goods travelled further, cities traded with cities, armies and builders reached places they could not supply before. Every road, mill and machine that came after sits on the same round idea.