Well, I kept thinking about the book, and now I think I've hit on the plot I missed as I was reading - (SPOILER ALERT!) - This book is about Joan's search for love, particularly a father's love.
The first couple of chapters in the book were gripping to me, when Joan was trapped on the family farm and engaged in a battle of will with her father, who was harsh and unloving and who blames Joan for the death of his wife (Joan's mother). He can't understand Joan's love of learning, and he doesn't value all the work she does around the house. Piece by piece, he strips away everything that gives Joan an escape from the drudgery of her life, until finally, in retaliation for her defiance, he burns her precious books. He's a despicable character, and like Joan, we hate him. We celebrate when she carries out her clever plan to run away.
(MORE SPOILERS!) The story then has Joan going through a series of crushes on the men in the family that hires her on. First, there was Mr. Solomon, the family's oldest son, who finds Joan on the street when she first gets to Baltimore, takes her home, and convinces his mother to hire her. Solomon is a gentle, kind, scholarly man, and we can understand why Joan would have a crush on him. There's also the father of the family, who is kind to Joan and lets her use his library after her day's work is finished, as long as she doesn't stay up so late that she oversleeps the next morning when she's supposed to help with breakfast. Joan herself doesn't write about Mr. Rosenbach in a romantic way, but she overhears Mrs. Rosenbach telling the bridge ladies about Joan's "crush" on her husband. Finally, there is the younger son, David, who takes Joan to an opera and buys her some art supplies and kisses her one night in the dark kitchen. Joan is completely enamored with David, and builds all kinds of dream futures with him in her mind. When she finds out he's leaving for Europe to study art, she recklessly begs him to take her with him, only to find that what she interpreted as love was just David's normal flirtatious manner.
Honestly, at the time I was reading it, I thought the story was trying to make a point about social class and romance, and maybe it was. But I like this newer explanation better. Joan never had love from her father or her brothers (no one had truly loved her since her mother died), so she is desperately trying to find a substitute for that lack. One article discussing research about parental influence concluded "children who feel unloved tend to become anxious and insecure, and this can make them needy." That description would certainly fit Joan through the whole novel.
The saddest part is, she still hasn't found it at the end of the novel. This is where the social class issue intersects with the psychological need issue. The Rosenbachs are kind to Joan, even to the point of providing her a scholarship to attend the new school Mr. Rosenbach has built, but there is a clear distinction between her and them. They are kind, but they don't love her. Pity or charity is not the same as love.
Or maybe Joan did find love, in the form of the grumpy old housekeeper, Malka.
She got up and came around the table and locked her arms around me. "You take that education," she said against the top of my head. "When life offers you something good, you take it, you hear me? You go to a good school, learn everything you can, and grow up to be a woman. That's what you'll do," she finished, and she held me so close I felt her old heart beating.
So I gave in. I even took a crumb of comfort, because she loves me. It wasn't what I would have chosen. I wanted David to love me, not Malka. But I guess I'm a beggar and can't be a chooser. Being proud belongs in novels.