"Consider that a toy steam engine was built by Heron of Alexandria around 2000 years ago, and yet nobody got the idea of harnessing it to replace human labor. P

"Consider that a toy steam engine was built by Heron of Alexandria around 2000 years ago, and yet nobody got the idea of harnessing it to replace human labor. Perhaps this can be explained in part by not-quite advanced metallurgy," Exactly, it is explained by not quite advanced metallurgy and tools. The steam engine works thanks to the small tolerances industrial lathes gave us that let a cylinder to carry a piston without fluids getting out. Watt had to create himself special tools for the creation of his engine. I have a link somewhere in my browser but zotero search is bullsh*t.