From Claudia Roth Pierpont’s “Tough Guy: The mystery of Dashiell Hammett” (The New Yorker [11 February 2002]: 70):
In March, 1928, [Hammett] had written to his publisher, Blanche Knopf, about his plans to adapt the “stream-of-consciousness method” to a new detective novel. He was going to enter the detective’s mind, he told her, reveal his impressions and follow his thoughts … But a few days after sending the letter, Hammett received one himself, from the head of the Fox Film Corporation, asking to look at some of his stories. He promptly fired off a second letter to Knopf, informing her of an important change in his artistic plans: he would now be writing only in “objective and filmable forms.” In the finished novel, Spade is viewed from the outside only, … we are granted no access to his mind. “The Maltese Falcon” may have been the first book to be conceived as a movie before it was written.