De Profundis, written by Oscar Wilde while he was in prison for homosexual acts, is a novella-length essay and memoir, directed towards his ex-lover, Lord Alfred Douglas. It was published shortly after Wilde's death. The title means "From the Depths", which could be interpreted in several ways.
I have heard it said of Van Morrison, another great Irish artist, that he could sing the phonebook and it would be beautiful. Although the format and subject matter might seem like poor material for 150 pages of writing, Wilde's wit, insight and phrasing are so well done that he gained my sympathy and interest. Anger at an ex-lover for being unfaithful and generally (as the kids would call it now) a douche is hardly a good model for universal prose on the human condition, but here, that is exactly what Wilde makes it.
This work also reflects Wilde's growing religious conscience, and a large part of it is dedicated to his admiration for Jesus. While he still puts a heavy emphasis on art, he seems to repudiate much of his prior image. One of the messages of this book is that beauty is different from appearance, and that "aesthetic" doesn't mean "shallow". (One of the more obvious meanings of the title).