More than two generations of readers have made Dashiell Hammett's Sam Spade their model of the hard-boiled private eye. They have enshrined Spade without knowing much about him. What they have overlooked is his heart. His toughness is leavened by both tenderness and subtlety; he has a feminine sensitivity to atmospheres and textures. Though basically a man of action, he doesn't exhaust his personality in man-talk or high-speed movement….

Hammett's complexity of insight brought new depths and tints to Black Mask fiction. These make Falcon a subtle study of moral behavior and of degrees of emotional commitment and stress. (p. 367)

Like much of American fiction, Falcon leans heavily on the head-heart dualism. But Hammett opposes the Hawthorne of "Young Goodman Brown" and The Scarlet Letter and the Faulkner of Light in August by rating reason over emotion. Spade's reason tells him to go against his heart, and, by...