Water power, someone else may have mentioned it, but water power was already used to power sawmills as possibly early as the 3rd century BC[1], I think a better

Water power, someone else may have mentioned it, but water power was already used to power sawmills as possibly early as the 3rd century BC[1], I think a better question then isn’t why didn't they build a computer, as much as why didn't they use their water power to industrialise? [1] http://en.wikipedia.org/wiki/List_of_Roman_watermills http://en.wikipedia.org/wiki/List_of_Roman_watermills