In a note to 3.2 of Gravity’s Rainbow, Weisenburger explains Pynchon’s use of the word “Tannhäuserism” as follows:

The tragic error of Tannhäuser — for example, in Richard Wagner’s operatic version of the myth — was to postpone his quest in order to linger for one year of sensual, “mindless pleasure” with the goddess Venus under her mountain called Venusberg.

For further details, I’ve taken the easy route and discovered from Wikipedia (also, Wagner’s version) that legend has knight/singer/poet Tannhäuser discovering Venusberg and lingering there for a while. Venus being the goddess of love, one assumes that he frolics and fornicates a bit, much to the consternation of God and, if I read it correctly, sort of behind the back of one Elisabeth, whose heart he later wins back with a song (just how it always goes, eh?). Further hilarity and songmaking ensue, and poor Tannhäuser goofs up again, praising Venus to the point of basically insulting Elisabeth to her face, when she’s poised to give the winner of what amounts to an old Teutonic rap battle the wish of his choice — which I presume to be a setup for betrothal. Tannhäuser screws it up to the horror of the court and goes looking for the Pope to seek absolution. The Pope replies that it’s more likely that his own staff will  sprout blossoms (I’m going to snicker here for Christine’s benefit) than that Tannhäuser will be forgiven, and Tannhäuser goes back to Venusberg dejected. Three days later he arose from the dead the Pope’s staff in fact blooms, but our venery-seeking poet is gone forever.

The Wikipedia entry adds this:

The legend has been interpreted as a traditional folk tale which has been subject to Christianization where the familiar story of the seduction of a human being by an elf or fairy leads to the delights of the fairy-realm but later the longing for his earthly home. His desire is granted, but he is not happy, and in the end returns to the fairy-land.

Well of course this makes me think back to an earlier post in which I noodle a bit on the costs of succumbing to temptation. You may recall that I considered Pointsman’s temptation alongside Slothrop’s. It turns out that Pointsman also has a subterranean Venusian connection (which I discovered by landing on this pretty much by accident). In 1.13, we find this (emphasis mine):

Surely the volume preceding The Book — the first Forty-one Lectures — came to him at age 28 like a mandate from the submontane Venus he could not resist: to abandon Harley Street for a journey more and more deviant, deliciously on, into a labyrinth of conditional-reflex work in which only now, thirteen years along the clew, he’s beginning to circle back, trip across old evidence of having come that path before, here and there to confront consequences of his younger, total embrace… But she did warn him — did she not? was he ever listening? of the deferred payment, in its full amount. Venus and Ariadne! She seemed worth any price, the labyrinth looking, in those days, too intricate for them…

So, as Pointsman ventured into the labyrinth of science as if at the behest of the love goddess beckoning from under Venusberg, Slothrop too now goes into the tunnels of the Mittelwerke, where he is taunted (though nobody’s actually aware of the fact) by what amount to gnomes singing of a man horny for a rocket. And just as Pointsman’s quest for knowledge has lured him into the confusing labyrinth of his work, Slothrop’s quest for knowledge of Imipolex G has led him underground as well, to the very place where the object of his unwitting affection has been forged.

Interestingly, for Pointsman, the labyrinth is a place to have been avoided. His thoughts as laid out in the quote above suggest regret, a wish that he had heeded the warning not to enter the labyrinth. Slothrop’s view of the underworld seems less — or at least differently — depressive:

There is that not-so-rare personality disorder known as Tannhäuserism. Some of us love to be taken under mountains, and not always with horny expectations — Venus, Frau Holda, her sexual delights — no, many come, actually, for the gnomes, the critters smaller than you, for the sepulchral way time stretches along your hooded strolls down here, quietly through courtyards that go for miles, with no anxiety about getting lost … no one stares, no one is waiting to judge you … out of the public eye … even a Minnesinger needs to be alone … long cloudy-day indoor walks … the comfort of a closed place, where everyone is in complete agreement about Death.

This poor fellow, who has an increasingly keen and correct sense that he’s been watched all his life, and never more openly or oppressively than as at present, just wants a refuge.

Like Tannhäuser, Slothrop’s had the odd carnal dalliance or two himself, debatably with more outwardly catastrophic consequences (or at least associations). I’m a little ahead in the reading and am in a position to give you the head’s up that the Tannhäuser theme continues to appear. So if it’s a thread that interests you, keep your eyes peeled.