Ian Logan's impressive study of what has become known as Anselm's ‘ontological argument’ found in the Proslogion covers the philosophical and historical ground in an imaginative and scholarly fashion. Convinced that Anselm's oft referred to argument has been confused and mislabelled, Logan begins with a fresh translation and exhaustive commentary on the Latin text. Prior to his translation, Logan considers what he refers to as the ‘pre-text’ origins of Anselm's philosophical ruminations based, interestingly enough, in Boethius' discussion of Aristotelian dialectic and Augustine's analysis of the human mind as ‘imago dei’. Logan defends what he takes to be the definitive account of Anselm's argument. He then traces this argument majestically and in a workmanlike fashion through medieval, modern and contemporary philosophy of religion. He argues that too often what a specific philosopher took to be Anselm's argument was at best a variation of the structure of the argument. In particular, Logan directs his attention in some detail to three major philosophers in the western tradition who discussed Anselm's argument: Aquinas, Kant and Hegel; in each case, Logan argues how these philosophers misconstrued the structure of Anselm's argument. This is especially true of Aquinas's reading where Logan identifies seven recurring objections to the argument in Aquinas's texts. Logan argues, following insights of Brian Davies, that Kant's all-persuasive dictum that ‘Existence is not a predicate’ does not affect Anselm's argument. Yet Logan suggests that Davies's analysis is too dependent on a Fregean concept of existence, which Logan argues is not a necessary condition to reach the same conclusion. Modern philosophers come in for much criticism for reading Anselm's argument in ways that Anselm did not adopt; this is especially true of the Cartesian rendition and those rationalists following Descartes. Logan notes that Hegel's charge that Anselm's argument is reducible to a formal analysis alone misses the mark. In contemporary thought, surprisingly, Logan gives Barth credit for understanding fundamentally what Anselm was up to in ways that philosophers not attuned to the interplay of faith and reason miss. Logan considers the usual array of contemporary philosophers of religion who take seriously the ontological argument: Hartshorne, Plantinga, Malcolm, Adams. Others less well known in this venue like David Lewis and Brian Leftow also come into play. Of particular interest is Logan's refutation of a possible worlds argument that some propose will provide provability to Anselm's argument. In the end, however, this reviewer is still plagued by Aquinas's worry about the ontological argument going from esse intentionale to esse reale without a suitable metaphysical bridge. In the mid-twentieth century, Jerome Shaffer rendered much the same structural objection. To paraphrase Aquinas, if what the ontological argument provides is a conceptual apparatus that ‘God must be thought of as existing’, it is still another question whether or not this concept holds beyond the mind. Logan considers a form of this objection but only in a rather strict Humean-like empiricist endeavour; Aquinas adopts an empiricist background for his metaphysics but he does not stop there. None the less, Logan provides us with an impressive monograph well worth serious study by both philosophers of religion and historians of philosophy and speculative theology. What Logan demonstrates is that failure to know the history of a philosophical problem renders incomplete and inadequate most philosophical analyses.