The Fat Man. That's how we're first introduced to our villain, Caspar Gutman. Wealthy, cunning, and obsessed with a black bird, Gutman is initially described almost exclusively in terms of his excessive weight:
Spade went in. A fat man came to meet him.
The fat man was flabbily fat with bulbous pink cheeks and lips and chins and neck, with a great soft egg of a belly that was all his torso, and pendant cones for arms and legs. As he advanced to meet Spade all his bulbs rose and shook and fell separately with each step, in the manner of clustered soap-bubbles not yet released from the pipe through which they had been blown. His eyes, made small by fat puffs around them, were dark and sleek. Dark ringlets thinly covered his broad scalp. He wore a black cutaway coat, black vest, black satin. Ascot tie holding a pinkish pearl, striped grey worsted trousers, and patent-leather shoes. (11.39)
Beyond simply giving us a physical image of Gutman that we can visualize in our heads, what else does this description provide us with? What can we infer about Gutman's personality or background from this description of his physical appearance? And why might it be fitting that our villain is a "flabbily fat" man?
Gutman is a figure of excess, and the fact that he's overweight is another sign of his excessive lifestyle. He's rich and can buy anything he wants, yet he is driven by an uncontrollable desire for the unattainable falcon. We always want what we can't have, right? Gutman takes that to the extreme and sees nothing wrong with offing a few people to reach his goal. He's even willing to go so far as to give Wilmer to Spade as the "fall guy," saying that Wilmer is replaceable, whereas there's only one falcon. Now that's harsh.
Despite Gutman's ruthlessness, he does have one thing that we can't really criticize him for: at least he's honest about his ruthlessness. He doesn't deny the fact that he only cares about getting the falcon, and unlike Brigid, he doesn't try to hide his criminality.
This makes him a different kind of antagonist figure in comparison to Brigid, who uses her femininity to feign innocence. We're not saying that Gutman doesn't lie or try to play tricks on Spade (he does drug Spade at their first meeting, after all), but Gutman is very upfront about his desire for the bird, so Spade at least knows Gutman's full motivations.
At the climax of the novel, when Gutman discovers that the falcon is a fake, we would think that he'd finally give up his fruitless search and find something else to occupy his attention. But Gutman refuses to let go of his obsession, vowing to return to Egypt to track down the elusive black bird. In the end, the fact that Wilmer kills Gutman for betraying him emphasizes the idea that Gutman is unable to maintain healthy human relationships due to his relentless pursuit of wealth.
Ultimately, Hammett seems to suggest that this single-minded fixation on a pointless goal not only destroys Gutman's chance for happiness, but also reveals how the corrupting power of human greed. We'll say.