Pui Him Ip, Origen and the Emergence of Divine Simplicity before Nicaea (Notre Dame, IN: University of Notre Dame Press, 2022), pp. xx + 276. $85.00

This book is a revision of Ip ’ s Cambridge dissertation, which was overseen by Rowan Williams, the author of the book ’ s foreword. It nuances the doctrine of divine simplicity for modern systematic and philosophical theology, where simplicity is often understood in pro-Nicene/Augustinian or Aristotelian-Thomistic terms, by elucidating its historical development from Plato ’ s Republic through Origen. The two chief insights of this historical study are, first, that divine simplicity came to be formed and accepted in Christian theological discourse as a doctrine with ethical as well as metaphysical significance, and, second, that while modern commentators have seen the doctrine as inevit-ably leading to modalism, its historical development was in fact in opposition to the analogous third-century theology, Monarchianism. This book ’ s seven chapters have a tripartite structure, covering the philosophical background of divine simplicity (chapters 1 – 2), simplicity and trinitarian theology (here specifically, ‘ the nature of the Father-Son relation ’ rather than ‘“ fully Trinitarian ” theologies ’ [p.49]) before Origen (chapters 3 – 4) and finally, Origen ’ s the-ology (chapters 5 – 7). Chapter 1 is a narrow but able discussion of simplicity in Plato, focusing on the locus classicus of divine simplicity in Plato ’ s corpus, which Ip maintains is Republic 380d