Hans Boersma begins this book with a confession that is exceedingly rare among scholars. He wrote it to prove a point, he explains, but ended up changing his mind. He set out to “test my hunch that the premodern Platonist-Christian synthesis does not require us to abandon the goodness of matter and of history, but that instead such an affirmation of this-worldly realities is dependent on the participatory sacramental ontology of premodernity” (vi–vii). He has not given up this hunch altogether, but he has decided that Gregory of Nyssa does little to validate it. For Boersma, Gregory's theology of ascent goes too far in leaving material reality behind.

Boersma did not find what he expected, but what he did find deserves to be widely read. Gregory has become the poster child for those who see a bright future for the historical relationship of Platonism and Christianity. For classical theists, Gregory's Christian Platonism is not only coherent but also relevant, since he appropriated Plato, they argue, without sacrificing any important Christian claims. For some defenders of Gregory, the stakes are exceedingly high, because they believe that sacramental theology is inconceivable outside of the categories of Platonic philosophy.

Much of this retrieval of Gregory looks more like theological apologetics than historical research. That is, Gregory's thought is cleaned up so that he can be made presentable to modern concerns about embodiment and sexuality. If Gregory is not as helpful as many theologians today want him to be, the current revival of classical theism will suffer a serious blow. Boersma does not give up on that revival, but he demonstrates that many strands of Gregory's appropriation of Platonism should strike us as incompatible with the best of modern Christian convictions.

Boersma uses the idea of the body—with chapters on the measured, textual, gendered, dead, oppressed, ecclesial, and virtuous body—to focus his wide ranging text. His central question considers the relationship between Gregory's mystical theology of ascent and his sacramental ontology. There are certainly many passages in Gregory's works which deny that the created order is futile and affirm the necessity of embodied existence for spiritual progress. For Boersma, however, Gregory emphasizes the body only to deny it. “Participation is for St. Gregory almost consistently a spiritual rather than a material reality” (9). Gregory's defenders thus “do not do justice to his overall thought” (11). They try too hard to make Gregory our contemporary.

Gregory resists our modern appropriation, according to Boersma, because he thinks of space and time as worldly structures that will be overcome in the afterlife. Gregory is famous for his doctrine of infinite progress, and Boersma does not downplay the fact that this progress begins here and now. What Boersma discredits, however, are attempts by Gregory's defenders to make heavenly and earthly progress more continuous than Gregory permits. Gregory defines created nature in terms of extension or interval (diastema), but he denies this feature to humanity's final destination. Other scholars have tried to discern two modes of diastema in Gregory, but Boersma rejects the idea that Gregory left room for a quasi-spatial and quasi-temporal understanding of the eschaton.

A non-diastemic afterlife problematizes not only eternal progress but also the material world's share in the resurrection. Gregory solves this problem by severing matter from extension and interval. Matter is simply the convergence of intellectual properties, so it does not even have the slim substantial existence of prime matter's pure potentiality. (Boersma agrees with J. Warren Smith that Gregory rejects a hylemorphic theory of substance.) Matter is, to put it bluntly, more spiritual than material, which is why resurrected bodies will be able to make progress in eternity without need for space and time. Our resurrected bodies will be purely intelligible, becoming something like the thoughts of God.

Boersma thoroughly explores Gregory's use of the image of a mirror, especially as that reflects on his understanding of beauty. Beauty is not a property of objects but instead the manner in which material objects participate in intelligible reality. The mind is the true mirror of God, but things in the world can be a “mirror of the mirror” (126), which happens when we try to fathom God as the presence of what makes objects understandable. Beauty is immaterial, which is why Gregory can connect it so vibrantly to a life of virginity.

The material world, in Boersma's portrait of Gregory, is an instrument of spiritual discipline. That does not mean that we can treat each other as mere means to extrinsic ends. Gregory rejects slavery because humans are more than irrational animals. The soul is the image of God stamped onto our bodies, and our bodies are due respect because they carry that image, even if their material composition is ultimately spiritual in nature.

Another highlight of this book is Boersma's discussion of Gregory's sacramentalism (186–188) as well as his defense of Gregory against the common charge of moralism. With that defense, Boersma comes full circle. “For Gregory virtue is the means of escaping the measurable, diastemic character of this worldly existence” (216). In discussing virtue, Gregory comes to praise mutability as a positive good in human life, but Boersma shows how that discussion hinges on his identification of perfection with progress. Progress requires change in this life, but when progress becomes perfect in the next world, we will not be able to change because there will not be “a measurable standard that one either attains or fails to attain, and by which one can subsequently be judged” (226). We will always be infinitely distant from the infinity of God, even as we keep getting infinitely closer.