jean des essaintes is the last of a dynasty. after an extreme and unconventional life he's now a lonely, eccentric and nerves-sick man, who tries to replace reality with an artificial reality, a dream of reality, which thus becomes reality for him.
really this is novel without a plot, it was the intention of huysman to write about his thoughts, about history and art and poetry and science and not to tell a story. that's sometimes very interesting and other times annoying.
the reason that i wanted to read this book in the first place was because it's said to be the one that inspired dorian gray in oscar wilde's masterpiece the picture of dorian gray, which is one of my favourite books.
nowadays it's not such a shocker anymore but i guess it was at the time.