A few years ago, I had the pleasure of reading the first third of a book called A History of the World in 12 Maps (and the displeasure of having to return it to the library without reading the other two-thirds). This was the first time I had ever heard of T-O maps, and they are fascinating.
What is a T-O map? Well, it’s a medieval phenomenon, with one of the first known ones showing up in Beatus of Liébana’s 8th-century commentaries on the Apocalypse. About a century before that, Isidore of Seville provided a description of the known world:
[Etymologiae XIV.ii The globe]
1. The globe (orbis) derives its name from the roundness of the circle, because it resembles a wheel; hence a small wheel is called a ‘small disk’ (orbiculus). Indeed, the Ocean that flows around it on all sides encompasses its furthest reaches in a circle. It is divided into three parts, one of which is called Asia, the second Europe, the third Africa.
2. The ancients did not divide the three parts of the globe equally, for Asia extends from south to north in the east, but Europe from the north to the west, Africa from the west to the south.
3. Whence it is clear that two of them, Europe and Africa, occupy half of the globe, Asia the other half by itself. But the former pair are divided into two regions, because from the Ocean the Mediterranean enters in between them and separates them. Wherefore, if you divide the globe into two parts, the east and the west, Asia will be in one, Europe and Africa in the other.
There you have it! Encircling ocean, eastern half Asia, western half Europe and Africa. Everything you need to draw a world map. Right?
Right! Let’s do it!
This is my rendition of a T-O map, and it’s very similar to actual maps of this type. You’ll notice a few things about this map. One is that per Isidore’s description, it includes only Europe, Asia, and Africa. Also, east is at the top rather than north.
…oh, and there seem to be some minor accuracy issues. What was up with these people, anyway? Did they really think the continents were shaped like pie pieces?
You’ll be relieved to know that the answer is “definitely not”. They didn’t have the benefit of satellite images or even the more sophisticated methods of longitude measurement at sea that were developed several centuries ago, but medieval mapmakers knew perfectly well what these coastlines looked like. (At least the parts they could get to. They also knew that the earth is spherical, despite some disagreement over Isidore’s meaning in the quote above.)
No, what we’re looking at here is a world map designed to express an ideology or philosophy about the nature of the world.
In a way, this is true of even the most accurate maps today, if they include political boundaries—not to mention the inevitable distortions in any projection that make us choose which inaccuracies suit our purposes. Maps combined with sociological data are also used to enhance our simple knowledge of the earth’s surface; we love tracking the geographic spread of dialects, fast-food franchises, common sports injuries, and much more.
These examples may seem very different from the map above, but they give us an idea of why this type of map existed. I would argue that as humans, we like to look at the world and then superimpose a version that bestows it with a certain significance in terms of humanity.
To early civilizations, maps of the whole world were more useful as a philosophical aid than a navigational one—they would have smaller-scale charts and maps for that purpose, appropriate to the scope and speed of travel. Depicting the entire world was more of an act of explanation, laying out basic truths rather than exhaustive details.
In this light, the existence of T-O maps makes a lot of sense. It’s pretty clever: the T and O are obvious in the design of the bodies of water, but they also stand for the O and T of orbis terrarum, or “orb/circle of the lands”. (It’s also called an O-T map, but I prefer T-O.)
The orientation makes sense too, since medieval European culture was strongly Christian, and the idealized Jerusalem on the map takes center stage. Putting east at the top is a sign of orientation (literally!) toward both Jerusalem and the theoretical location of Eden toward the top of the map.
Even the regular shapes of the continents and waterways are understandable. This map shows a world with a fundamental sense of order and regularity, with everything laid out deliberately and sensibly within the encircling ocean. Just looking at it, I can feel the satisfaction it must have given to see human logic lining up with the natural order…even if you have to ignore all the little fiddly bits and fjords to make it work.To me, having an explanation doesn’t erase the strangeness of the T-O map. With our easy access to Google Maps, or just a printed atlas, the idea of picturing the world in such an idealized, inaccurate way seems incredibly foreign. However, it does make me think about the other ways I carry on the proud human tradition of remaking the world in my own mental image. As long as the world is bigger than we can comprehend, we’ll have to simplify it for our own understanding and sanity.
I do think it’s an improvement that we know about all the continents, though.
[Read more about T-O maps here, or get even one on a t-shirt! Explore the details of the Hereford Mappa Mundi, the largest surviving medieval map that we know of. And check out other early world maps, including some of the twelve featured in the book I mentioned.]