Mrs. Frankweiler's not around for most of Claudia and Jamie's adventures, but she sure is a force in the story. Maybe she's a mentor because she's old and wise. But maybe she's a mentor because she not only nudges Claudia and Jamie in the right direction when it comes to solving the mystery of the angel, but she also talks to them about how to think about things. Claudia and Jamie may be smart kids, but they don't possess the kind of wisdom that Mrs. Frankweiler can share with them. After she shares the secret of the angel, she says to them:
"I think you should learn, of course, and some days you must learn a great deal. But you should also have days when you allow what is already in you to swell up inside of you until it touches everything. And you can feel it inside you. If you never take time out to let that happen, then you just accumulate facts, and they begin to rattle around inside of you. You can make noise with them, but never really feel anything with them. It's hollow." (9.251)
Wise words from a wise woman.