It’s hard to know where to start with Delany. He’s not really been much within SF for a long time, and my favourite novel by him (and probably by anyone), while published as SF, mostly isn’t. Still, he started in the field, writing extraordinary works blending poetry, space opera and philosophy in a way that is very representative of the transitions the new wave brought about in the ’60s. If I had to choose the cleverest person ever to write SF, he’d be my nomination.
A good example of the early SF might be Babel-17 (1966), a novel where the threat from alien invaders is not in any sense physical: it’s their language. It changes the minds of anyone that it touches. We get spacecrafts and their crews, but these are not at all military or heroic in style – the characters are outsiders and poets and the like. The effect of the language embodies the Sapir-Whorf theory of linguistics, that language affects our perception and interpretation of the world, and a reaction against Chomsky’s ideas (much the more favoured at this time) that language is functional and natural. This approach to SF was new.
Some years later (1975) he wrote a book called Dhalgren, which has long been my favourite novel. It is sort of SF: a guy with memory loss wanders into a city that has been largely abandoned since some undefined ecological disaster left it blanketed in fog. He wanders around a bit and hangs out with people and stuff. It’s almost 900 pages, and parts are highly experimental, fragmented and unsequenced. I’ve read quite a few books twice, one three times, and this seven times.
His most interesting SF or fantasy, more or less, since then is the four Neveryon books, containing eleven stories of widely varying length. These are set in some fictional past word undergoing many transitions at once: the coming of writing, money instead of barter, rural to town living. It’s about language and narrative – the first story, over 70 pages long, is repeated as the last story, and of course by that point it reads very differently and carries new meanings.
Since then he has written some extreme hardcore literary porn: avoid most of this unless you have an extraordinarily strong stomach, though the early Tides of Lust, sort of a porn response to Ulysses, is far less unpalatable. I am not joking about avoiding these. Unless you want to read about disabled children being raped and lots of eating shit, these are not sexy.
I do recommend everything else (if you want straightish SF, as well as Babel-17 I recommend The Einstein Intersection and Nova, and any of the SF story collections), and his first book of autobiography, The Motion of Light in Water, is wonderful. As well as his polymath brilliance, his experience of being a black man who has at times ‘passed’ as white, and a mostly-gay man who has lived as straight (he was married for a while) give him a rare perspective on prejudice.