Almost surreal at times, this reworking of Orpheus and Theseus narratives is set on Earth after humans have moved along elsewhere (dead? gone? no idea) and some other wierdos have taken over. It has the normal far future/dying earth conventions: chatty old cryptic computers still running, mutants everywhere, decayed urbanicity, radiation, pastiche of surviving mass culture, &c.
Novel is structured by Foucault's political dream of a pure community, embodied by the leper colony: "non-functionals, idiots, mongoloids, and cretins" (6) are sequestrated in cages until they die. "Difference" regarding phenotype is not tolerated generally. Narrator is "different," but is not functionally impaired. Is involved with another "different" person, and when she is killed, narrator is off to take revenge. Villain is also "different." Later, at an ultra-urban place, "difference" is disregarded as provincial bigotry. So, something there.
Lots of barely comprehensible action and exchanges--it's a Delany book, after all.
Intellectual core of the book, eponymous intersection, arises out of the confrontation of Einstein, "who with his theory of relativity defined the limits of man's perception by expressing mathematically just how far the condition of the observer influences the thing he perceives" (128), with Godel, "who was the first to bring back a mathematically precise statement about the vaster realm beyond the limits Einstein had defined"--with an explication of incompleteness/undecidability--boiling down to "there are an infinite number of true things in the world with no way of ascertaining their truth. Einstein defined the extent of the rational. Godel stuck a pin into the irrational and fixed it to the wall of the universe" (id.).
Thereafter, "the visible effects of Einstein's theory leaped up on a convex curve, its production huge in the first century after its discovery, then leveling off. The production of Godel's law crept up on a concave curve, microscopic at first, then leaping to equal the Einsteinian curve, cross it, outstrip it. At the point of the intersection humanity was able to reach the limits of the known universe" (id.). So, yeah, damned interesting. I repsectfully contend that this is the real story, and Delany missed it by writing a neo-mythical love story about a pack of mutants. Delany would respond that I have given an Einsteinian rather than Godelian criticism, and that'd be a fair riposte.
Recommended for readers haunted by their million year old fantasies, persons in wrestling matches wherein the loser would be dinner, and those who must keep the genes mixing, mixing, mixing.