Everyone Knows the Earth is Round (even Thomas Aquinas)

Summa of the SummaLately there’s been an odd increase in the number of people promoting flat earth theories. What is fascinating, however, is how long humans (at least some of them) have known the earth was round. I just came across this quote from Thomas Aquinas:


“[T]he astronomer and the physicist both may prove the same conclusion—that the earth, for instance, is round: the astronomer by means of mathematics (i.e., abstracting from matter), but the physicist by means of matter itself.”

Summa Theologica, Question 1, First Article


When did Thomas Aquinas write this? Well, the Summa Theologica was written between 1265-1274, so somewhere between those years. And he writes this as if it is SO obvious—he’s just using it as an example that proves something else he wants to prove about theology. Isn’t it funny that educated people back then are assumed to “know” the earth is round? This kind of puts to rest the idea that the medieval church was somehow suppressing the knowledge that the earth was round until Columbus sailed to North America. (This inaccurate version of Columbus’ journey has been debunked a million times by now online, but you still constantly run into people who believe this is what happened, so I guess it bears repeating). It also expands our ideas of what medieval people knew. There’s a tendency to assume people nowadays are so much smarter than the people in the past, so we’re inclined to believe stories that make fun of people in the past who thought they’d sail off the edge of the world. I’m not saying not a single person existed in the Middle Ages who thought they could sail off the edge of the world—I’m sure such people existed! After all, we still have flat-earthers with us today! All I’m saying is that people haven’t changed much.


This quote is actually from Summa of the Summa—a shorter summary of the Summa Theologica by Peter Kreeft. It is much shorter than the actually Summa, but it is long enough! It’s actually the second time I checked this book out from the library, and I hope to make more progress on it this time around. If anything more strikes me, I may blog about it again.

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