Via Terry Teachout, a 1958 interview of Raymond Chandler conducted by Ian Fleming.
Listen to the entire interview here.
Bonus question... who is your favorite movie Marlowe?
While I will always be fond of Bogart, and there have been some interesting takes on the character, such as Robert Montgomery's camera eye view Marlowe in 1947's Lady in the Lake. There have been some odd Marlowe casting, most memorably Robert Altman's The Long Goodbye starring Elliott Gould. There have been faux Marlowes, like Burt Reynolds' Shamus which does not mention Marlowe but is definitely derived from The Big Sleep but in my mind, no one captured the hard-boiled, world weariness of Marlowe better than Robert Mitchum in the 1975 version of Farewell My Lovely