It's almost hard to believe that Raymond Chandler's novel The Big Sleep — which featured the first appearance of quintessential hard-boiled private detective Philip Marlowe — and Howard Hawks' hugely celebrated film adaptation — appeared within a mere six years of one another.  So hugely has the cultural landscape been shaped by the twin conceptions of the private eye, so resonant have both versions of the story proven over the decades, so incredibly influential have both Big Sleeps beein to film and literature that you might almost imagine the book was some sort of ur-text penned around the same time as the epic of Gilgamesh.  But in fact, when Chandler wrote what many consider to be his greatest work, it was very much in the pulp milieu at a time when that carried no hint of respectability.  It was later generations of critics who would rightly elevate Chandler from his pulpy surroundings into his rightful place in the upper eschelons of American writers; in 1939, when it was written, it was a popular entertainment and nothing more.  No one much realized at the time that they were witnessing the making of an American classic, the early shadings of film noir or the creation of something that would become like a second literary language to generations of writers.  The book would be filmed twice, in 1946 and 1978 (three times if you count the Coen Brothers' delightful, if not entirely canonical, updating of the story as The Big Lebowski); here we concern ourselves only with the Howard Hawks classic and not the well-intentioned but inferior remake starring Robert Mitchum.  Like the book, the movie illustrated that however humble the origins of a story, it could be elevated to the ranks of high art by placing someone at the helm who was supremely interested in his craft and determined to make the most out of what he chose to work with.  In a rare feat for literary adaptations, both the source novel and the film adaptation are masterpieces.  Here's why.

WHAT IT HAD:  Everything.  With Howard Hawks in the directing chair, William Faulkner handling the lion's share of the script, and the hugely popular duo of Humphrey Bogart and Lauren Bacall in the leads, the first film version of The Big Sleep was pretty well destined to be a classic, and it comes through on almost every conceivable level.  I've written elsewhere about how the film's conception of Philip Marlowe is uniquely great, thanks to the disparate but complimentary influences of the men who created him.  The film is also paced like liquid mercury, gorgeously costumed and set, cleverly written, beautifully filmed, and simply a pleasure to watch in every way.    

WHAT IT LACKED:  Not much.  There are two versions of the film floating around (both of which are included on the popular DVD release), and the earlier 1945 version is somewhat lacking when compared to the 1946 recut; it's not quite as well-paced.  Despite the terrific dialogue, the movie lacks Chandler's breathtaking prose, especially his phenomenal descriptive ability.  The city of Los Angeles is a character in all of Chandler's best work, and the fact that the movie was made on sets and back lots instead of with location filming hurts it somewhat, but much care is taken with the sets to make them as evocative of Chandler's L.A. as possible.  And sure, the plot is confusing to the point of being impenetrable, but so was the book — legend has it that Chandler himself didn't know who killed Owen Taylor.

DID IT SUCCEED?:  Without question.  The movie and the book of The Big Sleep are both undeniable classics, which is rare enough, but even rarer is the fact that they're both classics for pretty much the same reasons:  scintillating dialogue, strong central characters, intriguing support roles, evocative situations, and a highly trained professional eye envisioning it all for us.  Though Chandler didn't have a hand in writing the film, his book was brought to the screen by people who understood and appreciated his vision and his style, and it shows through in every frame.  What was taken out was the bare minimum needed for time constraints and other practical reasons; what was added did no harm to the book.  It's one of the very few examples in the history of film of such a harmonoius match-up of source material and adaptation, and that's why it's one of the greatest films of all time.