This is an impressive work. It is not a book just about Augustine's work ‘On the Trinity’, but on Augustine's trinitarian thought as a whole. It is a mature work, not written within a couple of months, but with years of thinking and rethinking. All this time has helped make the book what it is. I am pleased that it is a historical work, mainly for two reasons: (a) it sketches the development of Augustine's thought (this old model of German historical approach is always helpful), and (b) it places Augustine's trinitarian thought in a specific place in the history of theology. Of course, there are warnings in the Introduction that the book has neither the aim to offer a complete ‘history of Augustine's Trinitarian thought’ nor does it set out to be a monograph about the whole of De trinitate. In fact, the monograph starts with the early Augustine, sketching the ‘origins’ of his trinitarian thought, and the chapters about De trinitate intend to set out the fundamental lines of Augustine's thought in De trinitate. So I think we are allowed to read this book as a new approach to an old problem: how did Augustine's trinitarian thought develop into the mature form found in De trinitate? If we follow Ayres’ approach, three problems appear. I ask: (a) what about philosophy, (b) what about Manichaeism and (c) what kind of theology is regarded as the background to Augustine's trinitarian thought?