The after-life is a pretty well-explored destination, both in the sense that, if most of the world's great faiths are to be believed, all of us end up there, and in that it has been the subject of some of the most enduring works of literature known to humankind.
They include Dante's Divine Comedy, Milton's Paradise Lost, the Book of Job, Swedenborg's New Jerusalem and, juxtaposing traditional Christians evocations of heaven and hell with the modern era, James Joyce's A Portrait of the Artist as a Young Man.
It is Joyce's Stephen Dedalus, listening to a Jesuit priest describe in lurid terms the "Four Last Things" – death, judgement, heaven and hell, in the Christian formula – who ushers in John Casey's elegant, learned but accessible canter through all that we have ever imagined lies beyond death. Casey, a Cambridge academic, has something of a reputation as a controversialist, unafraid to speak his mind bluntly on a range of subjects beyond the college gates, and usually taking conservative positions guaranteed to inflame liberal opinion.
So I was half expecting After Lives, at the very least, to lambast the social ills caused by the loss of fear of damnation since mainstream Christianity abandoned talk of the Devil and the fires of hell in the Sixties. But, though Casey does indeed highlight the failure of organised religion to give a lead in a century which "may have been the most fruitful in producing earthly hells", there is nothing polemical or prescriptive in this account.
Instead, he concentrates on telling the story of how poets, playwrights, popes and theologians, among others, have tried to describe something that religions hold is ultimately ineffable, beyond words, and that non-believers prefer to see as a collective delusion that has prevented us facing up to the finality of death. Casey is a master story-teller with just the sort of encyclopaedic knowledge that enables him to tread lightly in this overview through what can easily become a morass of detail.
Each of his 17 chapters, arranged chronologically, guides readers through the attitude to post-mortem survival in particular and significant cultures. He starts with ancient Egypt and culminates in the Spiritualist movement of the early part of the 20th century, when the grieving relatives of those killed in the mass carnage of the First World War sought to assuage their pain by throwing open what had hitherto always been seen as the closed door between this world and the next.
You could quibble with some of Casey's choices. As he traces the development of the idea of judgement in after-life – not always there in the beginning, but subsequently laid on with a trowel by Christianity – he rightly heads for Mesopotamia and the oldest epic known to us, Gilgamesh. The problem is that Gilgamesh doesn't say that much about fate after death, and Casey – though providing one of the best précis of it I have read – seems to be straining to fit it in to what he sees as an emerging pattern.
I kept wanting him to include more on the part that Eastern religions play in the development of our hopes for eternal life. Yes, their attachment to samsara, the cycle of birth, death and rebirth, as part of reincarnation, seems at first glance to exclude a final, fixed heaven or hell, but most forms of samsara include the yearning for an eventual exit from the cycle to a land of the gods.
These are, however, minor points. Both the strength and weakness of the book is its impeccable scholarship on the sources through which our current, vague and almost child-like ideas about after life have grown. Short of reading Dante or Milton or Swedenborg yourself – the last of the three a bigger ask than the first two – you will not find a better short cut. It is, however, the work of one more fascinated by literature and the development of literary ideas than the sociology of why particular texts appear and appeal at different times.
If heaven and hell have survived at all, it has mostly been because we want them to. The reasons why people have believed them are therefore just as important as identifying which bits in the overall picture have been borrowed from whom.
And, of course, what is tantalising about the whole construction of the after-life, as it has come down to us, is that we can never reach a definitive answer on whether it is true or false. It remains the ultimate delectable but untested promise. Despite the efforts of the Spiritualists, no one has ever come back from the dead to tell us whether all or any of what is predicted actually happens.
Casey ends this enjoyable survey with an intriguing thought. "Those cultures that have been most serious in their beliefs about post-mortem punishments and rewards are also those for whom the choice between good and evil has a momentous, even cosmic significance. For good or ill, they have regarded the moral world within with the utmost seriousness."
While we discuss heaven and hell much less than once we did, and largely dismiss, save in horror films, talk of the Devil, we continue to fret about morality and to bandy around the word "evil". It tends to be used as the ultimate rebuke and be followed by a full stop or, better, an exclamation mark. In describing the history of heaven and hell, Casey has given evil back its historical context – or contexts. In doing that, he may arguably be making an important contribution to contemporary public debate.
Peter Stanford's 'Heaven: A traveller's guide' is published in paperback by HarperCollins