For better or worse, we always know what the characters in Sentimental Education look like. Let's take a look at just a few examples:
- Madame Arnoux: "Never before had he seen more lustrous dark skin, a more seductive figure, or more delicately shaped fingers than those through which the sunlight gleamed" (1.1.23).
- Rosanette: "her laughing white teeth, her sparkling eyes, her beauty, her gaiety, dazzled Frederick, and made his nerves tingle under the lash of desire" (1.8.217).
- Monsieur Arnoux: "a jovial blade of forty with frizzled hair. His robust form was encased in a jacket of black velvet, two emeralds sparkled in his cambric shirt, and his wide, white trousers fell over odd-looking red boots of Russian leather set off with blue designs."
- Deslauriers: "If he had been called on to risk his life for his friend, Frederick would have done so. But, as he was desirous of making as good a figure as possible, and with this view was most careful about his language and manners, and so attentive to his costume that he always presented himself at the office of L'Art Industriel irreproachably gloved, he was afraid that Deslauriers, with his shabby black coat, his attorney-like exterior, and his swaggering kind of talk, might make himself disagreeable to Madame Arnoux, and thus compromise him and lower him in her estimation" (1.9.89).
Hmmm… which of these things is not like the other? That's right—Deslauriers, the lower-class characters is the one who doesn't look all that snazzy. Appearances can tell us a lot about social status, and that fact doesn't go over Frederick's head either. After all, in order to appear handsome and well-off to the Arnouxes, he is willing to blow off his good friend just based on how he looks.
P.S. There is one thing that matters more to Frederick than looking good: Madame Arnoux. Check out this deal with the devil: "Frederick would have been glad to become deaf, infirm, and ugly if, instead, he had an illustrious name and white hair—in short, if he only happened to possess something which would install him in such intimate association with her" (1.4.267). Now that's saying something.
And by action, we mean total action and total inaction. The characters in Sentimental Education can really be separated according to how much action they take—or rather, how much they act upon what they want.
We know for sure that Frederick isn't exactly a go-getter. He lets the revolution just float past him like a television set on in another room, and it takes him twenty years to score with Madame Arnoux—even then, he flubs it up.
So does anyone do anything in this novel? Plenty of people would say no, but there are two characters who break the mold: Sénécal (whether you like him or not) and Dussardier. They don't function solely on personal interest, and they actually act on their convictions. Other than these two, though, it seems to be more about dreams and ideals than actual agency.