Professor Edmund T Rolls' book, Brain Computations: What and How, has now been reviewed in Brain, where it has been described as "the first complete attempt to summarize our current knowledge about computation in the brain". The book considers what is computed in each brain system; and how it is computed. The reviewer considers that this book may provide a grand unifying theory, with biologically plausible models of brain computations. The book review, and information about Brain Computations: What and How (Rolls 2021) Oxford University Press are available here.