What is some important background information about Raymond Chandler in relation to his novel "The Big Sleep"?

Chandler was evidently a meticulous craftsman and perfectionist, rewriting, and reworking his stories extensively before being satisfied with a final version. Though my opinion may be a minority one, from the evidence of The Big Sleep, this fact about the author is surprising. What struck me when I first read the book was what seemed the relative diffuseness of the story—and the difficulty I had in following it—in comparison with two of his other well-known novels, Farewell, My Lovely, and The Long Goodbye. There is an anecdote to the effect that Chandler admitted that in The Big Sleep, even he did not know for sure "who done it."
Possibly because The Big Sleep was the first of his books featuring Philip Marlowe, a private detective who has achieved an iconic status, and possibly because the title is so evocative, it is arguably the most famous of Chandler's novels. The fact that it was filmed with Humphrey Bogart as Marlowe (and with Bogart's real-life wife Lauren Bacall) added to its reputation. Though I didn't know this at the time I read the book, Chandler had based much of it on material from short-stories he had already published in magazines. In my view, however, the best way to understand the essence of The Big Sleep and of the novels by Chandler as a whole is to compare him with the other detective/crime novelists of his period of similar reputation, especially Dashiell Hammett and James M. Cain.
Chandler's prose is similar to Hammett's in its directness and crisp, unadorned quality. But if we look at Hammett's Sam Spade in comparison with Chandler's Marlowe, Spade seems to possess even more of the rebellious, anti-hero feature that became a cliche of the standard private-eye persona. Both authors tend cynically to view the establishment through their central character, but Chandler's is a more subdued, subtle form of subversiveness, and one with which the reader can more fully empathize. Interestingly, it's possible to examine James M. Cain in relation to Chandler even more directly, given that Chandler co-wrote the screenplay for the film Double Indemnity, based on Cain's novel. Though the basic story-line is kept largely the same (though with a very significant change to the ending) what strikes one most is how completely the dialogue is transformed by Chandler. There is a characteristic phrasing (usually referred to as "hard-boiled" of course, though the term hardly does justice to it) and rhythm in the characters' speech that, in my view, none of the other authors were capable of producing as well as Chandler did. This is evident throughout The Big Sleep and even redeems whatever shortcomings the novel might have, especially near the close when the iconic statement occurs that nothing really mattered except that "he was sleeping the big sleep." The phrase carries an entire universe of meaning with it—echoing Hamlet's famous soliloquy—and endows the story with a universality it might not otherwise have had.