I enjoy Lydia's farewell note to Mrs. Forster for the way JA uses it so perfectly to illustrate her character. Lydia spends as much time asking her friend to make her excuses to one of the officers for not dancing with him that night, and to remind the servant to mend a tear in one of her dresses, as she does on her intended elopement. It's as if she expects to come back to Brighton and take up right where she left off, except when she comes back she'll just happen to be married!