In Chapter 5, the narrator compares Gloria to a "startled child" via simile:
She stretched out her arms with a gesture of freedom. This was what she had wanted, to stand alone where it was high and cool.
“Gloria!”
Like a startled child she scurried along the plank, hopping, skipping, jumping, with an ecstatic sense of her own physical lightness. Let him come now—she no longer feared that, only she must first reach the station, because that was part of the game. She was happy.
This simile demonstrates Gloria's childlike nature. Here, her motions—"scurried," "hopping, skipping, jumping"— reveal the most positive aspects of her youthfulness. She remains energetic and robust for most of the story. However, there are also many negative aspects of her childlike nature. Much like a child, Gloria is dependent on others for financial and emotional support. She also demands many comforts from Anthony, from reassurance to tomato sandwiches served at a particular time. Her whims and desires drive their travels, exploits, and purchases.
When Anthony finds her playing in this manner, she calls him "old, worried Anthony," an epithet that reinforces his position as the older and more responsible person in their relationship. In this scene and many others, Gloria praises him when he agrees with her and dismisses him when he displeases her. She never considers what she might bring to their relationship beyond her own beauty and charm. And even more striking than her childish habits and demeanor is the fact that she refuses to bear children for fear that pregnancy will mar her beauty—another sign of her overall lack of maturity.
In Chapter 7, Anthony reflects on his personal and financial failures. He compares desire to a sunbeam via simile:
Because desire just cheats you. It’s like a sunbeam skipping here and there about a room. It stops and gilds some inconsequential object, and we poor fools try to grasp it—but when we do the sunbeam moves on to something else, and you’ve got the inconsequential part, but the glitter that made you want it is gone—
Here, Anthony expresses frustration at his own tendency to chase illusory dreams and experiences. He conveys the fleeting nature of desire by comparing it to a sunbeam that skips randomly around the room. Not only do desires change, but they also change one's perception of an object's value. As Anthony says, desire "stops and gilds some inconsequential object" that might be useless, or even harmful. When the sunbeam of desire moves on to gild something else, one realizes the inconsequential nature of what it once illuminated.
Much like a sunbeam, desire can seem beautiful and even life-sustaining. The parallel between beauty and survival is important given Anthony's compulsion toward beautiful things that makes them seem absolutely essential to his existence. The significance of the sunbeam simile is that it demonstrates Anthony's growing self-awareness. He learns that desire is not to be trusted—desirable things aren't always as vital to life as they appear. And yet it also shows his unwillingness to change; despite his intellectual explanation of how desire "cheats" him, he remains unable to quell his own greed for money, beauty, and high society.
