Here is how George Luck begins his Vergil and the Mystery Religions, a chapter in his book Ancient Pathways and Hidden Pursuits:
In his Divine Legation of Moses Demonstrated on the Principles of a Religious Deist (2 vols [1737-1741]) Bishop Warburton proposed an interpretation of the sixth book of Virgil's Aeneid which seems to be almost completely forgotten today. None of the handbooks, none of the recent books on Virgil, none of the commentaries (not even Norden) seem to know of it, and yet this theory may provide the key to the understanding of Aeneas' descent into the underworld. One of the reasons for this curious damnatio memoriae could be the character of Warburton's book. It is full of bold and controversial ideas which are presented with considerable learning, but also in a dogmatic and sometimes presumptuous way manner. This manner obviously annoyed Gibbon, the historian, who published in his youth a scathing review which he did not care to sign with his name. It must have made a certain impression on the scholars of that time, for C.G. Heyne, the well-known editor and commentator of Virgil praises the anonymous author as doctor ... et elegantissimus Britannus. In later years Gibbon himself admitted that he had treated a man who deserved his esteem with contempt and regretted the "cowardly concealment" of his name in a personal attack.At this point Luck introduces what I consider to be a rather clumsy contrasting comparison between Homer and Vergil, claiming that "in six or seven centuries Homer's dreary panorama [in the Odysseus' famous Nekyia ritual in Book XI of the Odyssey] of hell has been brightened."
The time has come for a fresh examination of Warburton's views. It should be said that he seems to have taken most of his material from the Eleusinia of Ioannes Meursius (1579-1639), and this was held against him at the time. But the idea which electrified the whole mass of evidence was his own, and we are concerned with the idea. It is also true that many of his arguments are specious. On the other hand, material which he could not have known seems to support his view.
In the sixth book of the Aeneid Virgil's hero, led by the Sibyl of Cumae, descends into the underworld to consult his father, Anchises. The ceremonial of his entrance is elaborate, and as we follow him on his path the geography of Hades with its inhabitants unfolds before our eyes ....
The reason I find this "contrast" so clumsy is that Luck himself, as will be seen in his own words below, denotes Plato and the Mystery Religions as the two main sources of this supposed "brightening". But Plato's chronological position in that span of "six or seven centuries" between Homer and Vergil is no closer to the latter than the former. And the Mystery Religions are older still, for they were already well established in the time of Socrates.
But let's now return to George Luck:
There were two main sources of light: Platonism and the mystery religions. Both forces are so complex that they cannot be defined here. Even in Virgil's time there was no general agreement as to what Plato said, and central message as well as the ritual of the various mystery religions was still a well-kept secret, though certain allusions which would mean nothing to ordinary people were apparently tolerated. We find such allusions in Pindar, in Sophocles, in Isocrates, in Cicero, in Apuleius, and though they are deliberately obscure and ambiguous, they all seem to point to a message of hope beyond extinction and a promise of life everlasting. Such a message can also be found in the sixth book of the Aeneid.Several pages later, Luck gets back to Warburton:
Pindar, for instance, praises in a famous fragment (137 Snell) the man who has "seen those things" before he descends into the underworld, for he "knows the end of life, and he knows its beginning, given by Zeus."
.... A passage from one of Sophocles' lost plays (fr. 719 Dindorf = 837 Pearson) provides a parallel and a commentary: "Thrice happy are those mortals who, having seen these rites, go to Hades; for they alone are allowed to live there; to the rest all there is bad."
Warburton wrote, "The descent of Virgil's hero into the infernal regions, I presume, was no other than a figurative description of an initiation, and particularly a very exact picture of the spectacles in the Eleusinian mysteries, where everything was done in show and machinery, and where a representation of the history of Ceres afforded opportunity to bring in the scenes of heaven, hell, purgatory and whatever related to the future state of men and heroes ...."Want to know more? Well here's a link to Warburton's book (The Divine Legation), the whole thing is available free online! And here is a link to a detailed analysis of Warburton's thesis written by Thomas Taylor (a contemporary of Warburton and Gibbon), who mostly concurs, but hardly uncritically, with Warburton's main conclusion. And here is a link to Luck's book containing the essay Virgil and the Mystery Religions.
.... I shall not list all of Warburton's arguments, only those that seem plausible or significant, but I shall present them in modern terms and support them with new evidence, wherever possible. In doing this it would have been awkward to separate his thoughts from my own in every single instance. I have therefore decided to state his case as he might do it today, with all the tools of modern scholarship and the research of two hundred years at his disposal. At the same time I should like to refer readers to Warburton's book, which, for all it's eccentricities and prolixity, still makes excellent reading.