A book decomposition of a manifold is a way of decomposing it as a union of codimension-1 submanifolds (the pages) that are glued along a codimension-2 submanifold (the binding). For example, each fibered knot gives a book decomposition of the 3-sphere; more generally, every odd dimensional manifold has a book decomposition by work of Alexander, Lawson, and Quinn. In this talk I’ll explain why even-dimensional hyperbolic manifolds do not have book decompositions. The main tool is Morse complexity, a norm on singular homology introduced by Gromov for which we give some new computations for locally symmetric manifolds. This is joint work with Fedor Manin and Shmuel Weinberger.