In the case of Against Hierocles we thus get some sense of how the pagan argument evolved and was refined in detail over time, an evolution which required new responses on the part of the Christians. And Eusebius’ Against Hierocles is, among other things, such a response to a new development in the pagan argument. But matters are more complex if we turn to Porphyry’s Against the Christians and Eusebius’ response to it. Not only does Porphyry know a lot more about Christianity than Celsus did, but, unlike Celsus, Porphyry already has at his disposal a good deal of fairly sophisticated Christian apologetic literature which he can exploit for arguments against Christianity, or to which he can at least adapt his arguments. It seems that we are now at a stage at which the Christians themselves significantly contribute to the evolution of the pagan argument by their response to it, or by their anticipation of possible pagan objections.
But let us begin with the question why Eusebius thought that he had to write Against Porphyry in the first place, given, for instance, that he assumes that Origen had already answered all substantial objections. An answer presumably has to begin with the trivial fact that Porphyry wrote almost a hundred years after Celsus, and that he wrote after Origen. So we would expect that his attack on the Christians would contain some new elements that Origen had not yet addressed. One such element may, for instance, have been the comparison between Apollonius and Jesus. In thinking about Porphyry’s originality, though, and about how Eusebius judged it, it does seem to me to be relevant to keep in mind that Eusebius had claimed that Origen had anticipated all serious objections to Christianity, a claim, I take it, made in full knowledge of Porphyry’s treatise. So we should not think that the mere fact that Porphyry, writing after Origen, may have advanced some arguments not yet addressed by Origen will suffice as an explanation of why Eusebius wrote Against Porphyry. More important here seems to be the fact that Porphyry did not just write after Origen, but wrote knowing Origen, knowing some of his work—indeed, it can perhaps be argued, exploiting his work. Porphyry certainly made Origen a prime target of his attack against the Christians. We know too little about Porphyry’s treatise to be able to reconstruct even its overall line of argument. But to judge from Eusebius’ remarks in his detailed discussion of Origen in book 6 of the Ecclesiastical History, a crucial thrust of Porphyry’s argument was this: it was directed against Scripture, arguing that the Scriptures could not possibly contain the truth, which one could then extract from them, if one approached them with the right understanding and recovered their deeper meaning by allegorical interpretations. For they were full of contradictions, written by ignorant people of questionable character, liars, and forgers. So much one could already read in Celsus. But Porphyry obviously put his enormous learning and ingenuity to showing this in detail both for parts of the Old Testament and some of the accounts in the New Testament. And he alleged against Origen that, being a Greek, being steeped in Greek culture, being familiar with the best of Greek philosophy, the most sublime truths of Hellenicity, he had apostatized and had tried, using the Greek philosophical method of allegory, to read Greek doctrines into these worthless barbarian writings. In particular, Porphyry noted (Eusebius, Ecclesiastical History, 6. 19. 8) that Origen spent all his time with Plato, and occupied himself with the writings of Numenius and Cronius, Apollophanes, Longinus, and Moderatus, but also used the books of Cornutus and Chaeremon, from whom he learned the allegorical method. Now Jerome tells us (Letter 70. 4) that Origen wrote a Stromateis in ten books in which he compared the views of Christians and pagans and tried to support Christian doctrines by referring to corresponding texts in Plato, Aristotle, Numenius, and Cornutus. As Harnack has already observed, it is difficult not to suspect that Porphyry, in the text quoted by Eusebius, is thinking of Origen’s Stromateis.
Unfortunately, Origen’s Stromateis, too, is extant only in some fragments. But the impression which we get from these fragments and the relevant testimonies is that Origen in the Stromateis at least in part dealt with a variety of difficulties in the Old and New Testaments, among them difficulties which played a role in the Christian—pagan controversy. Thus, according to Jerome, Origen dealt in both the ninth and the tenth books with problems raised by Daniel—for instance, the story of Susanna (Jerome, On Daniel, 4. 5 ff.; 9. 24; 13. 1). Origen’s Stromateis may well have been in part apologetic in character. If, then, we assume that Porphyry was familiar with the Stromateis, we have to wonder whether Porphyry did not rely on material provided by Origen himself for his arguments against Christianity. We noted briefly above that Origen had chided Celsus for not having noticed discrepancies in the Gospels concerning Jesus’ genealogy, which had been the subject of controversy among Christians and between Christians and pagans. Origen’s contemporary, Julius Africanus, had discussed the matter; he himself did deal with the subject (Homily on Luke, 28), and Porphyry returned to it. Without knowing more about Porphyry’s Against the Christians, it is difficult to arrive at a firm conclusion, but we certainly have to consider the possibility that Porphyry, in criticizing the discrepancies between the different accounts of Jesus’ genealogy, also relied on Origen. We also know from Eusebius, Ecclesiastical History, 6. 3i. i, that Julius Africanus wrote a letter to Origen suggesting that the story concerning Susanna in Daniel must be a forgery, and that Origen wrote a detailed reply on the matter. In fact, both letters are still extant, transmitted as part of the catenae on Daniel. We have seen that Origen also dealt with the question in the Stromateis, which Porphyry seems to have known. It, too, seems to have been a matter taken up by Porphyry, who then argued that Daniel as a whole was a forgery and involved prophecyex eventu, thus undermining the claim that Scripture proved its status by its prophecies which we can see to have been fulfilled. Thus, we have to wonder to what extent Porphyry used Origen for his argument against the authenticity of Daniel. It would also be worthwhile to pursue the question of whether, and to what extent, Porphyry relied on Origen’s Against Celsus.
However that may be, a further crucial fact about Porphyry’s attack is that, whereas Celsus was obviously an unknown, insignificant philosopher who only received a rather belated answer because Origen quite reluctantly acceded to Ambrosius’s wish, Porphyry was the most distinguished philosopher of his day, a man of great learning, moreover, whose views could not easily be overlooked and dismissed out of hand. There is a further fact to which I will return later: Porphyry’s philosophical views were surprisingly similar to Origen’s and Eusebius’, and to those of like-minded Christian authors. Eusebius himself, for instance, relied on Porphyry’s writings, and quoted from them extensively. And Porphyry certainly did not at all fit the image of the idolatrous pagan whom Christians liked to paint in polemics against paganism. So there was further reason to take Porphyry seriously as an opponent. But even setting this point aside, it should be obvious why Eusebius thought that Porphyry’s treatise needed to be answered, even if in his view it contained little of substance which Origen had not already addressed. Given Porphyry’s enormous reputation, given that he represented the most advanced stage of pagan criticism, perhaps in this relying on, and taking into account, Origen’s arguments, an answer was needed.
Eusebius may have believed this all the more so, as Methodius had already written a short refutation, in not more than one or two books, which Eusebius would have regarded as inadequate. Jerome (preface to Commentary on Daniel) tells us that it was a refutation only ‘in part’, presumably meaning that Methodius responded only selectively to Porphyry’s arguments. But, given Methodius’ extant remains, and given in particular his vehement opposition to Origen and the kind of Christianity which Origen represented—namely, one decisively influenced by Platonism or even, as Methodius saw it, a Christianity adulterated by pagan philosophy—it is difficult to imagine that Eusebius, who did not even care to mention Methodius in the Ecclesiastical History, thought that Methodius’ response to Porphyry was adequate.
However this may be, Augustine’s Letter 102, can serve as evidence that a strong need was felt for an adequate response. As Augustine tells us in the Retractations, a friend, whom he wanted to convert to Christianity, had sent him six questions which needed to be answered, especially since some of them, the friend claimed, had been raised by Porphyry. So Augustine set out to answer them in Letter 102. It seems that the mere fact that they had been posed by none other than Porphyry made it appear particularly urgent to respond to them. So Eusebius, in writing Against Porphyry, will have tried to address this need. And again, one can easily see why Eusebius would think that he, rather than, say, Methodius, was particularly qualified to respond to such a learned work by a philosopher as Porphyry’s Against the Christians, but also why he would feel that he owed it to Origen to respond to an attack specifically singling out Origen and the kind of understanding of Christianity he represented.
But from Augustine’s response we can also see, at least, in part what kind of audience Eusebius may have had in mind. Eusebius must have meant to address at least a group of highly educated persons who were sympathetic to Christianity, but impressed by the kinds of argument Porphyry had to offer, and who, for this reason, either would not convert or would remain wavering in their commitment to Christianity. It must have been a group of persons whom Eusebius could expect to be able to afford to acquire a twenty-five-volume work, to have the leisure to read or at least consult it, and to have the education to follow and appreciate its detailed argument. But for reasons which perhaps become more apparent when we consider the Preparation and the Demonstration, I am also inclined to think that Eusebius thought that a Christian, even if he was firmly committed to Christianity, ideally had to have an answer for the questions Porphyry had raised, because Christianity was not a matter of mere—let alone blind—faith, but ideally a matter of a careful consideration and critical evaluation of all the available evidence, including the difficulties raised by Porphyry.