Since at least Plato, geometry has been held up as the model of abstract thought, and great thinkers have sought its origins. Particular, modular “languages of thought” have been invoked to explain humans’ unique cognitive achievements in some domains, including geometry. Contrary to this hypothesis, I propose that human geometry is largely rooted in navigation-like mental processes that merely approximate Euclidean geometry and are shared by humans and nonhuman animals. Humans uniquely can access this geometry with natural language and use it flexibly in novel contexts, ultimately supporting our capacity for formal learning. I thus provide a model for cognitive explanations of uniquely human knowledge that relies on the interaction between our evolutionary cognitive inheritance and our species-unique natural language.