When introducing Jordan Baker, the central image Fitzgerald uses is that of a balloon billowing slowly in wind that is entering a space where it doesn't belong and that is soon to be trapped there and soon to stop upholding that which billows in its currents.

... their dresses were rippling and fluttering as if they had just been blown back in after a short flight around the house ... the caught wind died out about the room and the curtains and the rugs and the two young women ballooned slowly to the floor.

This compound image of balloons dancing lightly on trespassing wind, then deflating as the trapped wind dies is supported by the secondary image of Jordan as one who is physically as well as, by implication, psychologically balancing something.

Fitzgerald has Nick see her as balancing something on the tip of her chin. An upturned chin had a stereotypical meaning representing the disdain of upper classes for anyone but themselves and representing the ennui--the listless lack of interest coming from dissatisfaction and satiation with pleasure and luxury--that compelled the upper classes at this period of elitist wealth and opulence in American history.

The overall image of Jordan Baker as blown aimlessly by a wind that will soon be exhausted leaving her stranded and as balancing psychologically complex feelings (satiation and disdain) are solidified by Fitzgerald's tertiary image of Jordan as an otherworldly, unreachable being as she and Daisy sit side by side in white dresses, the spotless purity and lightness of which is belied by the "impersonal" look in her eyes that accompanies the desireless satiation that fills her [satiation: excess that disgusts and wearies].

... a bantering inconsequence that was never quite chatter, that was as cool as their white dresses and their impersonal eyes in the absence of all desire.

Though she is very feminine, " a slender, small-breasted girl with an erect carriage," Nick also describes Jordan Baker as being "like a cadet": "an erect carriage which she accentuated by throwing her body backward at the shoulders like a young cadet." This description is not just limited to her posture. Like a cadet on watch, she keeps an alert but somewhat removed eye on everything. Also, she is possessed of a cadet's wariness; Jordan doesn't often let herself slip.

Earlier in the scene, when Nick says something that temporarily breaks her veneer, Jordan is quick to recover her exterior pose. Her overly enthusiastic outburst "surprised her" and she "yawned with a series of rapid, deft movements" and "stood up in the room." Jordan, like a cadet, has momentarily stepped out of line (even while she appears to be holding it up) and quickly rejoins the formation.

The formation, in Jordan's case, is to appear to love the ease of the non-demanding "good life." However, it is clear that she is bored. Unfortunately for other characters, Jordan will relieve her boredom at their expense.