This is a truly Abelardian book: not only does it discuss some recent developments in Abelardian scholarship, but it also develops, while doing so, important theses about the job of the historian of philosophy. Thus, it reproduces in its own way the complex structure which still makes many of Abelard's own works such fascinating reading.

The four dimensions mentioned in the title are, in Marenbon's words: first, the present of the authors studied by the historian of philosophy, i.e. their lifetime; second, their past, i.e. ‘their teachers, predecessors and … sources’; third, ‘their future’, i.e. their reception; and fourth, ‘the relation between the past thinkers and philosophy today’ (p. 1). By applying this scheme to aspects of Abelard's philosophical work, Marenbon forcefully argues that all four dimensions have to be taken into account by anyone who is doing history of philosophy:

As examples of the four dimensions, Marenbon discusses first the chronology of Abelard's works, clarifying the chronology of his logical writings, and second Abelard's relationship to Anselm of Canterbury. He shows that no serious engagement by Abelard with Anselm's theses can be demonstrated. As for Abelard's future, Marenbon shows that Abelard's argument that God cannot do otherwise than he actually does, was well known, in an anonymous form, to many medieval thinkers, due to its presence in the Sententiae of Peter Lombard. This is not a new insight, but Marenbon shows that reactions were very different and that it was probably Aquinas who came closest to understanding Abelard's original intention. This is interesting. First, because Aquinas shows a remarkable similarity to Abelard in other areas too, especially in the doctrine of conscience, and, second, because an acceptance of Abelard's argument coheres with Aquinas's conviction that God created a world of intelligible and sensible substances, because this was the most convenient thing to do. Furthermore, Marenbon shows how Leibniz, as a result of the sources that he used, overlooked the fact that his own theodicy was quite close to that of Abelard. The last part of the book is a balanced discussion of some recent attempts to parallel Abelard's theory of signification and his ontology with some recent strands in analytic philosophy. Marenbon shows, correctly, the limits of such a comparison. However, he could have gone further by stating that the history of philosophy can and should be a starting-point also for criticising contemporary approaches, if they do not reach the complexity of their historical predecessors or ignore some of their important insight. In this way, the history of philosophy, which is so brilliantly presented and defended in this book, becomes itself really a piece of philosophy and treats historical authors in accordance with its own philosophical spirit. However, every historian of philosophy, while never losing sight of this final aim, is well advised to take all the, sometimes painful, but always fascinating steps, which Marenbon proposes in this remarkable book.