From ch 14:

my stupid sister has mistaken all your clearest expressions. You talked of expected horrors in London — and instead of instantly conceiving, as any rational creature would have done, that such words could relate only to a circulating library, she immediately pictured to herself a mob of three thousand men assembling in St. George’s Fields, ... Forgive her stupidity. The fears of the sister have added to the weakness of the woman; but she is by no means a simpleton in general.

“Miss Morland, no one can think more highly of the understanding of women than I do. In my opinion, nature has given them so much that they never find it necessary to use more than half.