| Quote #1 Besides, he was rich; unlike most boys his age, he had never even begun collecting baseball cards. (1.2) |
Jamie is the first character in the book described as rich—and it's because he has a lot of allowance money saved up. That might not count for much in the adult world, but it sure does to Claudia, who can't even save up for a sundae sometimes.
| Quote #2 "Well, you see, Claude," Jamie whispered, "I have quite a lot of money." Claudia thought that old Jamie would end up being a business tycoon someday. Or at least a tax attorney like their grandfather. (1.44-45) |
In the book, it's obvious that some people have a better awareness of money, and others don't. Even though Claudia is older, she wisely realizes that Jamie is the one who has a knack for making and keeping track of money. And she… well she would probably blow it all on ice cream.
| Quote #3 Claudia appointed him treasurer; he would not only hold all the money, he would also keep track of it and pass judgment on all expenditures. (1.60) |
He who holds the money also holds the power—or something like that. Claudia may be the bossy older sister who plans the whole trip, but she lets Jamie have a say, too. He gets to stop her from making stupid purchases.