Lewis quote in Eldridge's book "Captivating"

[snappleman]

I was reading Stasi Eldridge's first book titled "Captivating". A Lewis quote was used to introduce the second chapter. Here's the quote:

"Even to see her walk across the room is a liberal education. "

Can you tell me what Lewis work is the source for this quote?

Thanks!

[Paul F. Ford]

He wrote this in a letter to Arthur Greeves 28 February 1917.

[signed]
Paul F. Ford
(author of the Companion to Narnia and the Pocket Companion to Narnia )