Allen, Pauline. Severus of Antioch. Routledge, 2004.
Pauline Allen’s selection and analysis of Severus’s text make a cogent case that he did not believe in a “tertium quid,” a new substance combined from Christ’s human and divine natures. Even if earlier fathers such as Irenaeus and Gregory of Nazianzus spoke of a “mixture,” Severus was more reluctant to do so.
Like others in this series, Allen gives us a portrait of Severus’s life, the larger Byzantine controversies, and a selection of his key writings. Her scholarship is top-notch and probably the best out there in English.
We need to distinguish between monophysite and miaphysite. Monophysite is not a term that Orientals gave themselves. Later Chalcedonians, many of whom would not have been in agreement with much of Cyril, used it to mean that the divine nature absorbs the human nature like a glass of wine absorbs a drop of water.
Miaphysite, on the other hand, means a specific hypostasis, the Logos, took on the properties of flesh. They would not cash it out between human nature and divine nature. For them, nature is a universal, and Jesus didn’t take on the universal of the entire human race. He took on specific properties.
Severus of Antioch said in Christ after the union there is difference but not duality. Severus is operating with the older Athanasian view that physis = hypostasis, existent reality. Because there cannot be “two existent Jesuses,” there can only be one hypostasis in Jesus. His opponents, by contrast, are working with a newer, post-Basil the Great, understanding of hypostasis and ousia.
In other words, a substance, on the post-Cappadocian reading, is the common property of a class, be it divinity or humanity. The problem, as Severus sees it, is to form a particular hypostasis from two common universals. As such, the common class of humanity would include all humans! Even worse, the whole Trinity would have assumed all of humanity!
Rather, following Gregory of Nazianzus, the whole Trinity “is above substance and above nature, and is not subject to these designations” (Allen, Severus of Antioch 85). Because substance is capable of division, we do not use substance (as such) to refer to the Trinity. The two “natures” are not “substances,” for they do not hold together many hypostases (87). Furthermore, because the two are not “substances,” divinity and humanity cannot create a new tertium quid (91).
I do not think Severus and his opponents had the same concepts in mind throughout the debate. That is not to say Severus was ultimately correct. I think there are some remaining difficulties in miaphysitism. That said, Severus was by far the best thinker on either side of the debate.
Ad Nephalium
Severus missed the opportunity to put his opponents on the horns of a dilemma: If the phrase “out of two natures” is wrong, and Dioscorus was wrong for using it, so says Leo, then was Cyril wrong for using it? If no, then Dioscorus agrees with Cyril. If yes, then Leo disagrees with Cyril.
Key point: in Christ after the union there is difference but not duality.
Severus is operating with the older Athanasian view that physis = hypostasis, existent reality. Because there cannot be “two existent Jesuses,” there can only be one hypostasis in Jesus. His opponents, by contrast, are working with a newer, post-Basil the Great, understanding of hypostasis and ousia.
Philalethes
Responding to a florilegium that tried to paint Cyril in a neo-Chalcedonian light, Severus shows where some Nestorians, replying to Cyril, used the phrase “in two natures.” Key argument: if you agree with Ephesus that you cannot divide into duality what is in union, how can you affirm two natures after the union (73)?
Contra impium Grammaticum
Key argument: it is hypothetically possible to make a mental distinction of two natures out of the union. Nonetheless, the language of “two natures after the union” risks affirming “natures which subsist separately and apart” (80).
Conclusion
Severus’s key arguments notwithstanding, it is hard to imagine a Western Christendom without Chalcedon. In other words, I doubt the arguments in this book will convince the average reader to become Syriac or Coptic. I do think they deserve careful attention. We believe in natures and substances, but we are not always clear on the nuances.

