This is a paperback reprint of the hardback edition of the same work originally published by E. J. Brill in 1992 in its series Studien und Texte zur Geistesgeschichte des Mittelalters. The text has not been altered but, in his preface to the reprint, O'Rourke lists five of his own articles, published between 2001 and 2004, which bear on the background of the book. While expressing surprise at the need for a reprint, the author declines to reply to those who engaged the original because he is ‘happy to accept their criticism and comments as legitimate’. In commending Notre Dame Press for reprinting the book and giving it a more accessible format, we may note some of the reasons for the book's success. While by no means the pioneer in studies on what Aquinas took from the Neoplatonism Dionysius transmitted or of his transforming use of it, the completeness of O'Rourke's survey of the vast quantity of relevant (and often untranslated) text, as well as his extensive knowledge and prudent employment of the multilingual literature, make it a genuinely useful resource for scholars – especially those in the English-speaking world where both the fundamental works and their results have been generally unknown. The clarity of O'Rourke's writing, and recognition that most of those interested in Thomas no longer read Latin, puts the book into the hands of undergraduates as well as specialists. It is not, however, only what it makes available which commends this monograph; the reliability of the judgements is equally important. O'Rourke is free from much of the polemic and exaggeration which has characterised most treatments of Thomas's relation to Neoplatonism. This comes out in the title which combines ‘Pseudo-Dionysius’ and ‘metaphysics’. Aquinas is neither protected from all taint of Neoplatonism in the Gilsonian manner (for example), nor do we find the exaggerated emphasis on his apophatism characterising Heideggerian readings – Aquinas remains a metaphysician. For O'Rourke the philosophical theology of Aquinas balances both the self-diffusive good and esse as principles. O'Rourke's balance and his enthusiasm for placing Aquinas within the Platonic tradition – particularly its participation metaphysics – is primarily owed to his following of Cornelio Fabro whose reformulation of the hierarchy of being in terms of ‘intensity’ is intended to meet something of the Heideggerian criticism of ontotheology as well as to avoid idealism. O'Rourke reproduces this reformulation and Fabro's criticism of the Thomist best known to Anglophones, Étienne Gilson. Fabro produced the most sophisticated and abiding twentieth-century reworking and defence of Thomistic metaphysics and it is upon this philosophical edifice that O'Rourke was discerning enough to base his own treatment of Aquinas. It is worth noting, then, that the republication of Fabro's complete Opere is underway, a volume appearing in the same year as this book inspired by it. Thus, because of its exhaustive historical scholarship, its even-handedness and its continued philosophical cogency, the reissue of O'Rourke's book can be greeted with applause.