If you haven't heard of it before, the elevator pitch for Eifelheim is that it tracks to sets of characters: the inhabitants of the medieval village (with the parish priest as main character) who are trying to understand and help the shipwrecked aliens (who look rather like giant grasshoppers), and a couple of modern academics whose disparate fields (physics and analytical history) come together to show evidence that our first contact with another species was about 800 years before.
The modern characters border on being annoying, mainly as a result of being so very, very modern. But they take up at most 20% of the text space in the book, and eventually come to serve as some interesting counterpoint to the medieval characters, with whom I, at least, found myself much more in sympathy than the modern ones.
What makes the book fascinating is what a good job Flynn has done in getting across clearly and humanly the intellectual and religious cast of the high middle ages. There's been a trend in the last few decades within the academic community towards re-examining a lot of the old stereotypes about what the "medieval" period was actually about. Judging by this interview, Flynn's work benefited quite a bit from reading that scholarship:
Question: Your protagonist, the village priest, is extremely rational and logical. Aren't medieval clergymen, as well as the rest of the Christian world at that time, supposed to be unscientific?Much of what makes Eifelheim such a pleasure to read is how convincingly Flynn plays out the conversation between the village priest (who was trained in natural philosophy, philosophy, and theology in the universities of Paris, but has been lying low for the last decade as a parish priest after becoming a bit too involved in the radical politics of his day) and several of the scientists among the aliens, who have what in many ways is a fairly normal, modern, materialist point of view.
Flynn: The Middle Ages was an age of reason ... and yet we've been taught to think of it as an age of superstition. It probably glorified reason far more than the Age of Reason. The medievals invented the university, with a standard curriculum, courses of study, degrees and, of course, funny hats.
The curriculum that was taught consisted almost entirely of reason, logic and natural philosophy—or, as we'd say, science. They didn't teach humanities, they didn't teach the arts, they taught essentially logical reasoning and natural philosophy. If you wanted to be a doctor of theology, a churchman, you had to first go through a course in science and thinking.
This was an era where the most celebrated theologian of all time was Thomas Aquinas, who dared to apply logic and reason to the study of theology. In fact, theology is the application of logic and reason to religious questions. They must have elevated reason to a pretty high pedestal if they were willing to subject their own religion to it.
In the Middle Ages, they first learned how to apply mathematics to scientific questions. After the time of the story, Nicholas Oresme, who was mentioned briefly in passing, was able to prove the mean speed theorem in physics using principles of Euclidean geometry, which marks the first time a theory had been proven by using mathematics, as opposed to us[ing] mathematics to describe the angle of refraction or to do surveying.
Although listening to a medieval Aristotelian/Thomist discussing cosmology with an advanced, materialist, star-farer makes for a lot of fun (at least, if you're in medieval cosmology) what most readers will probably find much more compelling at a human level are the religious discussions that go on between the human characters and the aliens. The Krenken, as the German villages term the aliens, find the idea of caritas somewhat alien, especially when applied across classes -- which in their species remain very rigid, due to their insect-like heritage. The religious dimension of the story is very well rounded, with the pastor's rationalism balanced by the strong but at times theologically fanciful faith of a young Minorite Franciscan who is staying in the village, and a very interesting cast of other characters from the village and the manor.
I've heard Eifelheim compared to Doomsday Book by Connie Willis, another science fiction novel involving the period right before and during the Black Death. I liked Doomsday Book quite a bit, though I thought that in some places Willis' Episcopalian conviction that the medieval church in England had been more Anglican than Catholic felt a bit jarring at a historical level at times. Eifelheim is far from being as unrelentingly grim as the latter of of Doomsday Book, even when the plague does come to the village, yet I think that at a human level it is actually more powerful at a human level. The intersection of humans, aliens, Catholicism and the impending dooms of both the humans and some of their alien friends bring out some very interesting and important questions about humanity and Christianity, and some pretty good answers.
If there's weakness in the book, it's in the modern (or more properly, near future) segments, which take up maybe 20% of the books pages. There's a somewhat odd narrative choice to have these segments narrated first person by a minor character who comes in only very late in the modern narrative, giving you an odd first person but almost third person view. I've no idea why the author made that choice, and it's a bit jarring at times. The personal/relationship problems of the modern character also never see the sort of wrap up one might want to see -- living you with the impression that the medieval characters have it much more together than the modern ones. I'm not sure if this was intentional or not. I could almost wish that Flynn had dispensed with the modern plot entirely and instead wrapped with more concluding material in the medieval segment, perhaps with some of the events which evidently took place 20-40 years after the main action in that part of the book.
Overall, though, this is a very, very good book.