Why did she seem so important; and why was she so special? Of course, she was beautiful. Graceful. Polished. But so were many other things at the museum. (4.21)
With a description like that, how could we not zoom in on the angel statue and take a closer look?
It's obvious that the angel statue is the most important object in the book. But why? What makes it so special, and why do the Kinkaid kids (who can hardly respect the bed of an old, dead nobleman) decide to treat it with reverence and real interest?
First things first. The statue has some real value, which makes it irresistible to Claudia and Jamie, who consider $20 a fortune. And everyone else wants the statue, too—they're all jostling to see it.
It's not just the money that draws the crowds though—the angel represents a kind of special secret. It's the kind of art that makes people feel something when they look at it. Claudia puts it this way:
"If I owned such a lovely statue, I'd never sell it. Or donate it either. I'd cherish it like a member of my own family," Claudia preached. (9.68)
The angel statue is art in its highest form—something that people will look at, love, and want, even if they can't exactly tell you why. We know how important secrets are to Claudia (and Mrs. Frankweiler), and each person feels their own sense of secrecy when they look at this beautiful masterpiece.
Claudia and Jamie are on a quest to find themselves and to do something meaningful while running away. The statue definitely represents that search for meaning. The kids are pulled in by the mystery and intrigue of the statue, partly because they are searching for a reason to do something grand while they're running away. That way, they can return home as heroes.
The mystery of whether or not Michelangelo was the sculptor eventually consumes every part of their adventure. Angel is larger than life, and her mystery is the key to why Claudia and Jamie are running away and whether or not they can go back home without regrets.