I have a problem with Robert Morrison's Ch. 2 Note 9:

Mrs. Clay's surname is evocative, suggesting every-thing from low social status, to a malleability that will harden with time, to an idol's feet of clay.

"Feet of clay," while referencing a biblical story from Daniel, had its first known use in 1814 (www.m-w.com), or possibly 1855-60 (www.dictionary.com). It could hardly have been such a certain association as Mr. Morrison implies, if it had only been introduced a couple of years earlier. I think the other meanings might have been in Author Austen's mind, but I suspect that she was not trying to trigger the thought of a character flaw that is usually not readily apparent (www.m-w.com) or a weakness or hidden flaw in the character of a greatly admired or respected person (www.dictionary.com) as Mr. Morrison suggests.