The lives that human beings think they have, and the world that they believe themselves to inhabit, are simply the result of a minutely
imagined and executed practical joke. But what a joke! "The lengths we went to, the pains we took, that it should be plausible in every detail - planting in the rocks the fossils of outlandish creatures that never existed, distributing fake dark matter throughout the universe, even setting up in the cosmos the faintest of faint hums to mimic the reverberations of the initiating shot that is supposed to have set the whole shooting-match going. And to what end was all this craft, this labour, this scrupulous dissembling - to what end?"
The "we" who is speaking here - though he is quick to point out that the notion of speaking itself is alien to him and his kind - is the god Hermes, also known as Argeiphantes ("he who makes clear the sky"), Logios ("the sweet-tongued one") and Psychopompos ("usher of the freed souls of men to Pluto's netherworld"). And, despite his grandiose self-introduction and the book's macro-sweep of history, the matter that brings him among us is nothing more elaborate than the dying of one man.
That man is Adam Godley, a distinguished theoretical mathematician brought to the edge of death by a blood vessel that burst, in properly comic-bathetic fashion, as he strained on the lavatory. As he lies in a coma - past all hearing, sense or cognition, according to his doctors - his family gathers around him: his much younger wife, the clandestine drinker Ursula; their discomforted, awkward son, also Adam, writhing in too-tight, borrowed clothes; and their daughter, Petra, an unstable 19-year-old given to stark, infrequent pronouncements and bouts of self-harming. Behind them stands a familiar cast of ill-assorted, ill-at-ease characters: a dandified would-be biographer on the make, an unkempt and unfulfilled domestic, young Adam's restless wife, Helen, a silent cowman, and a mysterious, vaguely menacing stranger. Unaware of the presence of the immortals - Hermes is joined fleetingly by his randy father Zeus and the mischievous, uninvited Pan ("If he misbehaves," says Hermes crossly, "as I know he will, I shall box his ears, the scamp") - the human cast drifts unhappily about its business, waiting for a death to occur in an upstairs room.
That is our set-up, for a single day's action that thrusts us firmly between the vertiginous infinite and the inescapable particular, between the unknowable and the unacknowledged. This is Banville's territory and he knows it well, although his achievement is to make it strange and disturbing to his readers on each occasion. With the chutzpah to call the crumbling, folly-like Godley residence Arden, and to choose midsummer for his setting, he acts as a troublemaking god himself, setting Zeus to ravish Helen in her bed with Hermes holding back the dawn as distraction, shifting shape to arrange unlikely matches and thwarted seductions, ruffling the fur of an old dog to bring him face to face with a divine presence that only he can see.
What here is real, and what is important - "to what end" is all this, in the words of Hermes? Adam is not beyond consciousness or subjectivity; rather, he lies becalmed, moving through "the sad braggadocio of dying" to contemplate his work, the experiments on time and creation and multiple universes that, as his life closes, are simply "not enough". If he is to sift his experience for a moment of authenticity or clarity, where is he to find it - in what he describes as the endlessly unravelling and extending worlds of his researches, or in the apparently bounded spaces between the people who pace the rooms beneath him?
In fact, those spaces are not finite, and it is Banville's business to conduct us between the players, animating the chasms that suddenly appear in their stilted conversations and botched interactions, directing us towards their plaintive self-interrogations as they give way to quiet panic and half-apprehended epiphany. In the guise of Hermes, he is a knowing and humorous companion, comical and mournful by turns, blending portentousness and erudition with moments of whimsy and playful self-deprecation. His immortal self is, it seems, a way to make momentarily real what he seeks continually to intimate - the extent to which we are all in a state of startled surprise at things that seem to exist just beyond our plain sight.
In Banville's last novel, the Booker-winning The Sea, in which an art historian attempts to enumerate and elucidate his griefs, his subject was more overtly concerned with our attempts to define and accommodate loss; in The Infinities, we appear to be poised just on the brink of it, trapped in a limbo just before bereavement. Yet it is no accident that his central character is a man who has devoted his life to scrutinising the meaninglessness of such divisions: loss, we understand, is with us whether or not it has actually happened. The success of this novel - at an emotional level, at least - is to make us curiously optimistic to have got to the bottom of that one.