Written by two theologically-sympathetic philosophers, this is a wonderful discussion of every aspect of Anselm's thought, laying out precisely both the content of Anselm's theological discussions and the philosophical assumptions that they make. The writers are explicit in their admiration for Anselm, and this makes for a very agreeable read, even when they disagree with Anselm (as they frequently do), or find some of his arguments lacking from the perspective of contemporary philosophy. They do not engage much with secondary literature, but nevertheless make it clear when they are proposing something new, or something upon which there is a debate. For example, they take a very strong line on the novelty of Anselm's theological project, arguing that Anselm intended to prove God's existence, the doctrine of the Trinity and the doctrine of the incarnation, without presupposing any faith commitments, and they provide plenty of compelling evidence in favour of this reading. And they offer a very distinctive interpretation of the argument for God's existence in the Proslogion, taking as their lead Anselm's seeming failure to respond satisfactorily to the criticisms of Gaunilo. On standard readings of Anselm, right the way back to Gaunilo, what is crucial in Anselm's argument is the claim that existence is a great-making property. Accordingly, so it is argued, it is for this reason that that than which nothing greater can be thought must exist. Visser and Williams propose instead that Anselm's key assumption is that certain great-making properties entail existence – though they note too that Anselm only outlines what these properties are in his reply to Gaunilo. And in this case, as Anselm puts it, that than which nothing greater can be thought cannot be thought not to exist. The Fool in the argument, who thinks that God does not exist, is simply failing to think of God at all. As Visser and Williams note, their reading of the Proslogion brings it far closer to more standard versions of the ontological argument, and as they see it Anselm is unsuccessful because he fails to establish the truth of a key premise, namely, that God's existence is possible. Anselm states that that than which nothing greater can be thought exists in the understanding, which is his way of asserting that its existence is possible, since, as the authors show, he holds that only the possible is conceivable. But an assertion is not a proof. Overall, this is a highly sophisticated account of one of the greatest of Christian thinkers, and should certainly from now on form the starting place for anyone interested in understanding – and taking seriously – Anselm's theology.