The Alliance has been at war with the Invaders for decades. Now a series of damaging sabotages are occurring, each accompanied by a burst of communication in a new uncrackable code, Babel-17. General Forester calls in Rydra Wong, poet, ex-cryptographer and linguist extrordinaire, to help out. She quickly realises Babel-17 is not a code, but a remarkably expressive and powerful new language, and sets out to unravel it and track it down.
I had thought I was slowing down. Back in the 70s I could read three SF books in a day; today I have trouble reading one. But, after reading Babel-17 I realise it's not just me slowing down -- it's also the books getting longer. Without necessarily getting better. Delany crams as many ideas and images into 200 pages here as would fill a modern trilogy -- or worse. The port scenes, the discorporates and the use of Basque, the marvellous chaotic banquet, the aliens with their temperature-based language, the short half chapter with "I" and "you" interchanged -- are just some of the beautifully-crafted jewels in here.
But the main theme of the book is language. True, Babel-17 may be based on the Sapir-Whorf hypothesis, that language determines the way we think, which is currently discredited in its strong form used here. Yet much old SF is based on now-outmoded scientific theories or engineering limitations. What makes good old SF is when this doesn't in fact matter, because those (wrong) ideas are nevertheless used in an interesting and consistent way, and the story is still worth telling. As here.