This may get a bit involved, but it's probably worth it, so bear with me.
"...partly under an old print of a detail from the minor and soft-core Alexandrian mosaic Consummation of the Levirates" -- p 171
This is a fairly arcane joke. Apparently Hal, with his interest in Byzantine Erotica, has a print of a softcore mosaic in his room, but what's with that title. It *sounds* like one of your standard Art History painting subjects like "The Judgement of Solomon" or "The Temptation of Saint Anthony", but, of course it's not. But what is it? Well, to explain that, we have to talk about:
The Real Sin of Onan
Onan, as almost everybody knows, was killed by God for the heinous crime of "spilling his seed upon the ground". This, throughout history, has associated him with masturbation, beginning with the writings of Clement of Alexandria. And I agree, that when DFW mentions O.N.A.N., that connotation is implied. But that's not why God was mad at Onan. If you go read the whole sordid story in Genesis 38: when God killed Onan's brother, for reasons which are a bit obscure, leaving his widow childless, it was the custom that Onan was required to marry her and father a child upon her. This child would legally be his brother's. This was known as Levirate marriage. Onan didn't want any children who weren't legally his, so Onan "went in" to his brother's wife but pulled out early and "spilled his seed on the ground". So Onan's real sin was refusing to Consumate his Levirate Marriage. Now, once God whacked Onan, his widow had to wait for his remaining brother to grow up. But she got tired of waiting and put on a veil(!!!!) and tricked Onan's father into having sex with her. So a painting of the "Consummation of the Levirates" might be Onan's father banging his sons' wife....
What does this have to do with IJ?
- DFW just wanted nit-pickers to know that yes, he did know the real story of Onan?
- It's another Hamlet-like story of brothers and widows?
- It bears more than a passing resemblance to the convoluted relationships of the Incandenza brothers, J.O. (and if those aren't Onanistic initials I don't know what are, at least when I was growing up, around the same time as DFW, J.O. usually expanded to "Jack Off"), and the PGOAT/Joelle/Madame Psychosis?
- All of the above?