“Gravity’s Rainbow,” Thomas Pynchon’s gargantuan parable of rocketry, sex and a whole bunch of other stuff, turned 41 this year — six years older than its author when it was first published. What happens when a novel whose scenes of coprophagia and pedophilia moved Pulitzer trustees to cancel the prize in 1974 (when Pynchon seemed poised to win) eases into middle-aged, canonical respectability? Well, for one thing, it gets an audiobook release. Since the mid-1980s, a George Guidall recording has been floating around, like some mythical lost rocket part — no one had heard it, but all Pynchon fans knew someone who knew someone who had — but in October a new version, authorized and rerecorded and burned onto 30 compact discs — hit the stands. How on earth, I wondered as I stripped the wrapper, is poor Mr. Guidall going to render the sudden outbreaks of crazed capitals, or librettos in which stoners with guitars pastiche Rossini, the instructions helpfully stating “(bubububoo[oo] oo [sung to opening of Beethoven 5th, with full band])”? He turns out to do it in a slow and deep-voiced manner, beneath whose calm avuncularity you can detect anxiety, even mania, bubbling but never quite erupting — although I could have sworn I heard him, in the silence at the end of CD 30, racing out the door to buy a year’s supply of those Thayer’s Slippery Elm Throat Lozenges the hero Slothrop sucks, or perhaps to check himself into the book’s White Visitation mental hospital.

The main benefit of Guidall’s superhuman effort may well be ergonomic. Unlike Grigori, the novel’s reflex-­conditioned octopus, a human reader has only two hands; removing the book as a physical object frees up one of these to palm through Steven Weisenburger’s “A ‘Gravity’s Rainbow’ Companion” and the other to click around the many online glossaries to the text while listening. Such resources seem to me more than optional; only “Finnegans Wake” is more opaque, more reference-­saturated than Pynchon’s novel. And perhaps the benefits of audio end here. An old canard, reeled off incessantly by people who haven’t read “Finnegans Wake,” or at least haven’t understood it, holds that “you need to hear it spoken aloud in order to appreciate it.” This is nonsense: Joyce’s novel, wrapped around in silence, is all about legibility — inscriptions, codices, scattered scraps of paper in need of reassembly, exegesis or decoding. So it is with “Gravity’s Rainbow”: The book’s logic is entirely scriptural. Every surface in it is a parchment to be interpreted: ice-cracks form “graffiti . . . a legend to be deciphered”; raindrops splash in asterisks, inviting us “to look down at the bottom of the text of the day”; lit cigarettes trail “cursive writing”; even feces on the walls of sewers presents “patterns thick with meaning.” Its people, lying in rows in a hospital ward described as a “half-open file drawer of pain each bed a folder,” are legible as well, “poor human palimpsests” that doctors transcribe and — more sinisterly — rewrite. Slothrop’s ancestors, as Puritans, scanned the sky for messages, viewed all of nature as a ledger packed with data “behind which always, nearer or farther, was the numinous certainty of God.” In keeping with their sensibility, the narrative momentum thrusts both forward, toward inevitable (because predestined) final catastrophe and judgment and, simultaneously, backward, through histories encrypted into junkyards, light bulbs, even human hair, reverse-engineering cities into ruins, rooms to their “plan views” in order to lay bare the plans hatched in them, plans in whose web all current actors find themselves entangled. One character is tellingly urged, in a direct address by the narrator, to ponder a “wind tunnel” theory of history, through which tensor analysis might reveal “nodes, critical points,” turbulence-spots decisive in the shaping of all subsequent airflow, only now become apparent — then told, “Here’s a thought: Find a non-­dimensional coefficient for yourself.”

This restless contrafluvial parsing, this excavation of each layer in the substrata of the present, leads to a work that, were it written today, would be assigned the label “theory fiction.” Pynchon’s scanning and assimilation of a host of cultural histories and scientific archives, of the work of Pavlov, Max Weber, Robert Graves and others, is assiduous, even scholarly — if we imagine the most brilliant scholar dosed up to his eyeballs as he expounds urban theory, economics, folk mythology and differential calculus, all at the same time. Double integration in aeronautical guidance, the poetry of Emily Dickinson, weather reports gleaned from 1944 editions of The London Times — it all gets wound through Pynchon’s typewriter, held in formation by a rhetorical patterning lifted principally from Melville (like those of “Moby-Dick,” the most striking sequences in “Gravity’s Rainbow” typically begin with a statement of plain fact, then unpack this into a lyrical succession of images, which in turn set up a large conceit, before the chapter, often switching to the apostrophic/interrogative, climaxes in a burst of monumental allegory). It’s entirely fitting that the character we first meet, into whose dream we find ourselves inveigled, is one Pirate Prentice — a clear stand-in for the author: as pirate, brazenly commandeering and stripping other vessels; as prentice, learning (although not so slowly) on the job. Prentice is the recipient of the novel’s first, rocket-bomb-borne cryptic message; he it is whom his age tasks with “getting inside the fantasies of others: being able, actually, to take over the burden of managing them”; who saves his drunken buddy from crashing to his death from a balcony, but is unable to prevent the larger Fall, the screaming from the sky.

“Incoming mail,” thinks Prentice as he watches the missive-carrying V2 arc its way toward him in the dawn. But the V2, lit by the sun from below, also appears as a star, dragging a rainbow contrail. In this novel about clarity and obfuscation, about the Enlightenment’s most dazzling and dark consequences, light and its color spectrum play a central role. Light (like those feces in the sewer) is always patterned — trellised, meshed by lattices and trusswork; it, too, promises and withholds meaning, covering landscapes “in misty ambivalence” and turning people into “dark fish hiding past angles of refraction.” The rainbow, as a laying-out of chromatic intervals and syntax, would be nature’s way of parsing herself. But man, or rather the Man, has realized he can do this too: Enter IG Farben (“Colors”), developer and patent-holder of synthetic dyes and fabrics, not to mention Zyklon B; mother ship of BASF, Bayer and half the other big chemical industry names; funder over time of a range of political campaigns including but not limited to the Nazi Party’s; the “corporate octopus” (is this a first citation for the term?) for which Grigori is no more than a small stand-in, whose factual history Pynchon meticulously studies and then fictively embellishes, according it the role of the most critical of all point-sets in the tunnel. The logic and M.O. of IG Farben and its outliers is invasive transformation, artificial synthesis, control. Which also, of course, is the logic and M.O. of novel-writing. Pynchon fully appreciates the link: “How alphabetic is the nature of molecules,” he writes. “These are our letters, our words: They too can be modulated, broken, recoupled, redefined, copolymerized one to the other in worldwide chains that will surface now and then over long molecular silences, like the seen parts of a tapestry.”