The letters of Marsilio Ficino provide a rich treasury of information on the activities and interests of the Platonic circle in Florence and elsewhere at the end of the fifteenth century. They are also valued in their own right. It has therefore been surprising that a full critical edition has taken so long to appear. It was first conceived in the 1930s, and entrusted by Giovanni Gentile to the then young Paul Oskar Kristeller, Eugenio Garin, and Alessandro Perosa, who had the skills and the interest to complete the task, complex and difficult though it was bound to be. However, the advent of war and a subsequent failure of funding meant that the project was delayed by two generations. A first volume, corresponding to Ficino's book 1, appeared in 1990. The second volume of what should eventually be a twelve-part series is now at last before us, and it does not disappoint. In fact, it will be an essential working text for anyone seriously interested in Ficino, supplementing and generally surpassing earlier editions and part-editions.

This second book was set apart by Ficino as different from the rest of his collected letters, because it consists of a small number of philosophical treatises, all concerned with the theology of Plato, and therefore described as “divine in content” rather than “human” (3). It contains nine items all related to the mind's ascent: the five “Keys to Platonic Wisdom,” clear and simple outlines of ideas presented more fully in the Platonic Theology; a creative and imaginative dialogue, St Paul's Rapture into the Third Heaven; the well-known Argumentum (Introduction) to the Platonic Theology; a short letter to Alamanno Donati on the unity of the tripartite soul as expounded in Plato's Republic; and a treatise On Light as it manifests at different levels of creation, which was also published jointly with his treatise On the Sun as a separate book in 1493. To these canonical nine Gentile makes the valuable addition, as an appendix, of the volgare translation of St Paul's Rapture that Ficino prepared for Bernardo del Nero.

The book went through different forms between the first appearance of its individual items around 1476–77, their compilation for Federico da Montefeltro in 1482, their subsequent re-presentation to Lorenzo de’ Medici as the Opuscula of 1491, and their eventual inclusion, somewhat rearranged, as book 2 of the editio princeps of the Letters in 1495, followed here.

Gentile's introduction presents the fruits of his meticulous research on its development through the manuscripts and editions, with detailed discussion of the variants, corrections, and questions of dating. For a full account of the manuscripts themselves the reader needs also to refer to Gentile's previous volume, but this is to avoid repetition. Ficino's text is then printed in a fine clear font, with numbering of lines to allow easy reference to and from the critical apparatus shown at the foot of each page. There is no numbering of paragraphs. In a separate band are notes on parallel passages in other authors. Often these indicate Ficino's actual source, but sometimes the relationship between the passages is more open to question. Either way, the identification of such passages is helpful to anyone wishing to form their own view of Ficino's contribution. It is also yet another indication of the painstaking labor that has gone into the preparation of this volume. To cite just one example, in the Argumentum, where Ficino is adducing a proof of the soul's immortality from its power to understand incorporeal forms by itself and separately from the body, Gentile has provided the references to Themistius (105) that had eluded previous editors. He has also included the little-known Henry Bate of Malines, a pupil of Aquinas who had taken issue with Aquinas on the very matters discussed here. We do not know whether Ficino read Bate's Speculum divinorum et quorundam naturalium, but its inclusion widens our view on questions of considerable interest.

Among the comprehensive set of indexes provided, the list of sources and parallel loci displays an impressive network of cross-references within the body of Ficino's own work. It also reflects the importance of Aquinas, his entries numbering as many as those of Plato, Plotinus, and Proclus put together.

This book will aid the preparation of a full English translation, and one hopes that it also heralds the arrival of further volumes.