If we doubt whether this was even a rhetorical, let alone a real, question for Eusebius, it is easy to make the question seem more serious and urgent. If we look at Eusebius’ introduction to Against Hierocles, we see that he thought that among all the many apologies which had been written, there was only one fairly comprehensive, more or less definitive one: namely, Origen’sAgainst Celsus. In Against Hierocles, i, Eusebius tells us about almost all of Hierocles’ objections to Christianity:
These arguments, too, might at the appropriate time find their fitting refutation; but they already virtually have been overturned, even before anybody has written a treatise especially against them; they have been thoroughly refuted in advance in altogether eight books written by Origen directed against the work by Celsus entitled ‘True Account’ which is even more preposterous than [Hierocles’] ‘Friend of the Truth’. The author indicated [i.e. Origen] without fail has set matters right concerning Celsus’ treatise in as many books as I said; he has taken up altogether whatever anybody ever has said or will say on this subject, and has resolved the difficulty. We refer those who do love the truth and want to have precise knowledge of our doctrines to these books.
It is true that part of the reason why Eusebius refers to Against Celsus is presumably that he thinks that Hierocles has plagiarized his objections in part from Celsus. And it is also true, and hardly needs to be explained here in detail, that Eusebius is, and feels, thoroughly indebted to Origen. It remains the case that he commits himself to the remarkable claim that Origen has dealt satisfactorily with not only all serious past objections, but also pre-emptorily with all substantial objections which anybody is ever going to raise. So why, then, do we need Eusebius’ apologetic treatises? Obviously the answer to this question is highly complex, and will vary from treatise to treatise. What I want to try to pursue here is just one aspect of the answer to the question of why in particular he wrote the Preparation and Demonstration. But, before I turn to this, I want to briefly consider two other of Eusebius’ apologetic writings, Against Hierocles and Against Porphyry.
A first answer to why Eusebius wrote Against Hierocles lies on the surface. Hierocles in some detail, relying on Philostratus’ Life of Apollonius, develops the argument that Apollonius of Tyana was a truly divine man, without fail, more powerful and impressive than Jesus, who, especially in comparison with Apollonius, is open to criticism—for instance, in the way he failed to defend himself. If, then, Apollonius is not a god, why should we think that Jesus is God (Against Hierocles, I, 2, 37—9)? In Against Celsus Origen had briefly discussed Apollonius (6. 4i) in connection with Celsus’ claim that magic does not have any effect on a true philosopher. Origen ridicules the irrelevance of this remark, but from his answer it would seem that Celsus had taken the view that a true philosopher, unlike Christians and unlike Jesus, will have nothing to do with magic, to which Origen responds with a reference to Apollonius. But the way Origen responds in referring to Apollonius makes it clear that Celsus himself had not already drawn the parallel between Jesus and Apollonius to argue against Christ’s divinity. This is all the clearer in that we do find in Celsus (cf. Origen, Against Celsus, 3. 26 ff.) a rather similar argument concerning a list of persons which does not include Apollonius. We find in Celsus the argument that there are all these figures like Aristeas, Abaris, Hermotimus, and Cleomedes, who are credited with miraculous powers, but whom no Greek would regard as a god. Now these figures were legendary; so it must have been tempting to improve on the argument by replacing them with the historical figure of Apollonius, especially once his reputation had spread and Philostratus’ Life was available to document, as it were, his miraculous powers. This seems to be precisely what Hierocles did. For, to go by Eusebius’ Against Hierocles, 2. 10 ff., he had a similar list, beginning with Aristeas, but then introduced Apollonius as somebody fairly recent and hence, presumably, as somebody whose case was well documented. Thus Origen had not yet had the chance to confront this particular argument, let alone this argument as based on Philostratus’ Life, which had appeared only some twenty years before he wrote Against Celsus. Hence there was room for a treatise by Eusebius to deal with this new argument, a task he must have felt particularly well equipped for, since it involved subjecting Philostratus’ Life, the main source for the emerging cult of Apollonius, to historical criticism.
Obviously, a lot more would need to be said about this, but I will address just one point. It is not clear from Eusebius’ introductory chapter whether he thinks that even this particular argument in Against Hierocles, which he is going to focus his attack on, is entirely new, or whether Hierocles is original only in developing it in such detail and giving it such a prominent place in his overall argumentation. So the question arises as to whether Hierocles does not owe even this argument to an earlier source: not Celsus, but Porphyry’s Against the Christians. It is clear from Jerome, On Psalm 91 (Harnack, frg. 4) that Porphyry referred to Apollonius alongside Apuleius and the Egyptian Magi, already mentioned by, for instance, Numenius, as having worked wonders. But it is only if we assume that Macarius Magnes’ Monogenes is based ultimately on Porphyry’s Against the Christians that we have in Monogenes, 3. I (Harnack, frg. 63) evidence that already Porphyry compared Apollonius’ way of dealing with being taken to court with Jesus’ meek behaviour before Pilate and his ignominious suffering. This still is not yet the full argument we find in Hierocles, but a crucial step in its direction.
Before we leave Against Hierocles to turn to Against Porphyry, though, let us briefly consider the question of what audience Eusebius envisages for his writing. I have certain doubts in general as to how clear a notion authors have of their audience. But in this particular case Eusebius’ own introductory remarks perhaps provide the beginning of an answer. Against Hierocles is addressed to a person not named, but referred to as philotes, or ‘dear friend’ (ch. I) and hetaire, or ‘companion’ (ch. 3). He is perhaps a Christian. He is certainly rather educated, as Eusebius presupposes that he is thoroughly familiar with Philostratus’ Life of Apollonius. The introductory sentence strongly suggests that Eusebius’ correspondent has been rather impressed by Hierocles’ argument. This seems to imply that Eusebius’ correspondent represents a group of persons large enough for Eusebius to feel seriously concerned, persons who are well-to-do, well educated, sympathetic to Christianity, if not actually Christians, but certainly not firm enough in their grip on, or grasp of, Christianity not to be tempted by Hierocles’ arguments. Towards the end of Against Hierocles, Eusebius goes to surprising lengths to attack fatalism (43—8). This, of course, is prompted by remarks in Apollonius’ apology in the eighth book of Philostratus’ Life, but is hardly explained by it. One rather gets the impression that Eusebius thinks of his correspondent and the group he represents as being tempted by fatalism and the associated art of astrology, if not also by other forms of divination and other superstitious practices. One would in this context also have to consider the evidence for a growing cult of Apollonius. In short, one has to wonder whether Eusebius is not addressing himself to an audience which, for all its education, held on to superstitious pagan beliefs and practices. Though this is much later and in a different place, it may not be entirely inappropriate to remember that Augustine thought that many pagans, however sympathetic to Christianity, did not want to convert because they were attached to astrology and other forms of divination (cf. Sermon 374, lines 262 ff., Dolbeau).