Mary Bennet is around the age of 18 in the beginning of the novel.She is the most serious of all the Bennet girls; dull, plain, and almost to the point of pomposity.Mary enjoys performing for people on the piano (not always very well), but otherwise she is not very interested in local society, seeing balls as a duty rather than a pleasure.She is interested in social theory, especially regarding people's ideas on vanity and pride.Much of her time is spent in studying, but she tends to sermonize about many subjects in a fashion.