An interesting and useful book about the Middle Ages particularly if you want to go off and read primary source -- that was, in fact, its primary purpose, to give people information before they headed off to medieval works and either kept interrupting their reading to research what something meant, or misread it in blissful ignorance.
It discusses some currently obscure writers who were major influences.
It covers the structure of the universe and how it differs from the modern model; size is considerably less important than you might think, as, for one thing, medievals thought that the earth was the size of a mathematical point and you can't get any smaller than that, relatively. The influence of the planets, which was Science not Magic at the time. The inhabitants of the sphere.
The Longaevi, a term he used from "fairy" creating a false impression that has to be overturned before you get into the rather complex medieval treatment of the -- ehem -- Good Folk.
The structure of the Earth and the Five Zones -- two temperate, one torrid, and two freezing -- and you could not get through the torrid zone to the other temperate one. Medieval treatments of animals, which fall into fantastic and absurd bestiaries, or into hard-as-steel factual knowledge by authors who obviously have a lot more familiarity with the animals in question that most modern writers. Human bodies and the three kinds of souls.
Lots of interesting info.