Water Wheel

Flowing water drives mills - the first major power source that does not come from muscles.

Water wheels are documented in the Hellenistic world from roughly the 3rd century BC (Philo of Byzantium, later Vitruvius) and spread across the Roman Empire; the Barbegal mill complex near Arles (2nd century AD) is considered an early factory. For centuries water power ground grain, later it drove hammers, saws and bellows. It showed that natural forces can do work without anyone sweating.