Professionally trained theologians differed on so many things, so why, Ian P. Wei asks, should they have agreed on animals? But just as they shared certain fundamental theological tenets—the divinity of Christ, and so on—so too they shared certain fundamental tenets about animals, chiefly, that, unlike us, they had no rational soul and no hope of resurrection. And just as shared fundamental theological tenets establish a field for acceptably varied solutions to cruxes, so too the shared belief in animal irrationality and human rationality offered theologians the opportunity to hone their logical skills in service to a conclusion that was always, at any rate, foreordained. Though they saw no need to prove that nonhuman mortal animals lacked reason, they still needed to account for their behavior in all its variety without reference to free will, nonsensory cognition, the generation of universal categories, or other capacities held to be unique to rational beings. This puzzle was evidently one they thought well worth their consideration.Finding their considerations on this topic, however, takes work, as no medieval theologian devoted a stand-alone treatise to, for example, animal cognition. Learning what these writers thought about animals can require either compiling a florilegium clustered around certain themes—as Anselm Oelze did in his Animal Rationality: Later Medieval Theories 1250–1350—or simply reading straight through key works by a small but interconnected set of major thinkers. Wei takes this approach, with three chapters devoted to texts and writers produced by scholars all associated with thirteenth-century Paris: the first, longest chapter is on William of Auvergne’s De legibus and De universo; the second, on the Summa Halensis (a work expanded from Alexander of Hales’s notes by Jean of La Rochelle and others) and Bonaventure’s Sentences commentary; and the third, on books 20 and 21 of Albert the Great’s De animalibus, where he moved beyond commentary on Aristotle to his own thoughts on animals, and two works by Aquinas, the Summa theologiae and the Summa contra gentiles. All these men were in Paris when William of Auvergne was its bishop, and Alexander of Hales taught Bonaventure, and Albert the Great Thomas Aquinas.Wei’s method throughout is to paraphrase long passages from his theologians, while furnishing the Latin original in the footnotes, which is also where he engages with contemporary scholarship. Each chapter generally follows a trajectory from the most rigid treatments of human/animal difference to slight relaxations, where the theologians entertain observations about correspondences between our behavior and theirs. None of them ultimately reevaluate the old divide between humans and animals, but many are willing to consider likenesses, perhaps inspired by the new attention to animal behavior catalyzed by translations of Aristotle into Latin (or so argues Nigel Harris’s The Thirteenth-Century Animal Turn [Palgrave, 2020], a book more concerned with preaching and popular cultures than theology).Points that frequently interest Wei’s theologians include proving that the naturally upright human posture is evidence of their innate dignity, disproving the transmigration of souls between humans and animals, and demonstrating that animals cannot form universal concepts: though a sheep might fear all wolves, it never forms a concept of wolfishness; and though ants store grain against the winter, what they did was, according to Albert the Great, only a “sort of prudence,” without the true orientation toward ultimate felicity or the abstract logical thinking unique to the human animal. Per these theologians, we can learn all manner of things from animals, including laudable traits of fidelity and marital constancy, and humans can sometimes descend into a contemptible brutishness. But while animals can be trained, they lack free will, so they can never be anything but their own, merely sensual, mortal, predictable selves.Each theologian also had their own particular interests. William of Auvergne labors to justify God’s seemingly pointless command that the Hebrews sacrifice animals to him; he analogizes heretics to the obduracy of wolves to argue that each should be mercilessly extirpated. He is interested in strange forms of knowledge: through a complicated theory of “descending lights” and solertia, he likens the know-how of spiders and other crafty animals, or the legendary knowledge of a hedgehog that knew a tempest was about to batter Constantinople, to the instantaneous, nonpropositional knowledge of prophesy, available even to those humans in the grip of fury; he considers a woman whose husband so terrified her that she falls into a fit (“morbo caduco”) whenever he entered the house, though she had no conscious knowledge of his being home. William’s consideration of incubi and succubi includes a story of a Saxon knight who fathers several children with a bear, and whose children retain something of their maternal ursinity. Alexander of Hales and Bonaventure each wonder why God should have tempted us with a talking serpent. Alexander differentiates between proper and disordered killing of animals, suggesting that God may be something of a conservationist, and, in response to the question of whether Adam’s body was “animale,” he takes pains to split the rational animal, homo, from the otherwise undifferentiated mass of animals. He allows for a limited kind of “animal thinking” about God, confined to sensory things, which, Wei suggests, allows him to animalize the theology of non-Christians. Bonaventure concludes an otherwise standard list of why God created animals for us with a surprising, positive reference to pets; later, however, he insists that we love a friend’s dog not because of the dog but because it belongs to our friend. Albert the Great argues that the rational soul perfects even our vegetative and sensible powers—Bonaventure offers a similar argument—and insists on the hand as an organ unique to humans, while ignoring his own, later consideration of the multipurpose dexterity of the elephant’s trunk. Like Bonaventure, Aquinas argues that the rational soul does not come from potential in matter. And Aquinas differentiates between pleasure, common to humans and animals, and happiness, unique to humans.As Wei’s book is in essence a compendium of animal thinking from major thinkers working in the monumental mode, there is of course much more than this. If the book were longer, I would have liked to have heard more about both the sources and the possible novelty of some of this work. Augustine has a lot to say about animals, too, and Wei marks many of the agreements: but where, if anywhere, do these thinkers break with him? Like Oelze, Wei wants us to know that medieval theology is much more heterogeneous on animals than has been argued by other scholars. That heterogeneity, however, has a limit. While many theologians take animals right to the edge of reason, and in doing so, complicate their understanding of how our rational powers work, they still leave them there, far from us, doomed to mortality and to an instrumental existence.