Being an intensive look at the intensive work done in that era.
It opens with watermills, which were perhaps the biggest change. They were known in Roman times, but not implemented, sometimes explicitly to keep labor laboring. In medieval times, they were put to use. Grinding grain of course, but also for fulling cloths, tanning, and many other things, and then there were floating mills and tidal mills and eventually even wind mills that could turn to catch the wind. And how the mills came to be the first corporation, where you own a share in the mill and its profits. Often the miller was an employee. And the great rivalry over
The agricultural revolution with the horse collar. In ancient times, you were forbidden by law to weigh down your horse with more than a fraction of what they pulled in medieval times. This is because the ancient horse collar was just an ox's yoke. They rear back their heads in ancient depictions because they are trying to avoid choking to death. Medievals invented a serious horse collar, and got much more use from it. Especially as they also introduce nailing on iron horse shoes. Plus new plows, which made many parts of Europe arable for the first time.
To be sure this lead to environmental issues. Builders have plans that highlight how you can build them with short timber.
Clocks were also innovated widely. Weight-driven ones were devised. Many Catholic churches installed them, though the Orthodox rejected them.
It also goes into mining, labor conditions, architecture, and mathematics with other pure intellectual procedures.
The epilogue is not about the era at all, but about the claim that the United States has had it, and the whole thing is a bit flat in style -- the facts are interesting but rather dryly presented. Still, those who want to know about medieval machinery will find a lot here.