Best example of medieval ignorance?

[Angrboda]

This may be apocryphal and complete bullshit, but I'm going to tell it anyway.

A friend once told me of a popular game in medieval times. You would hang a cat by its tail from a pole or tree so that its body hung down at about head height. The objective of the game was to run at the pole and bash the cat against the pole with your head, thus killing the cat.

Yeah, it's probably bullshit, but it usually gets a laugh. As a consequence of my in-depth research at Wikipedia, it appears that the consensus of modern historians was that there was no actual "dark ages" caused by the Catholic church, but I'll leave it to historians and historically minded folk to fight that one out. A number of relevant points: 1) the ascendancy of Latin as the lingua franca of the literate classes, particularly within the church, meant that many of the texts on math, natural philosophy and philosophy were inaccessible, being written in Greek, 2) there were bright spots, the Carolingean renaissance for one, 3) there are other factors to bear in mind, such as the mini Ice Age and the impact of the plague.

Anyhoo. I've heard this book recommended enough times that it's probably worth passing along the recommendation: A World Lit Only By Fire, by William Manchester

Oh, and as long as I'm here editing, geocentrism was not an absurd position of the time, and the tale of Copernicus and Galileo is often told with mythological elements incorporated. One of the most important bits of the tale that is left out is that Galileo was forming his conclusion based on observations using the newly invented telescope. Astronomers prior to Galileo simply did not have access to the same data. Even then, Galileo still presumed the heavenly bodies to circulate in perfectly circular orbits, thus inheriting the age old assumption. It would have to wait for Kepler to correct this error. (It's also worth bearing in mind, too, that the predictions of Galileo and the Copernican model at that time were actually less accurate than Ptolemaic models used by Muslim astronomers of the time.)