Mrs. Bennet is one of three characters in Pride and Prejudice thought to mostly function as comic relief. Does Mrs. Bennet have another function in the novel?
It cannot be said that Mrs. Bennet "develops" through the novel, that is, that she comes to a greater understanding of herself or life, yet she is a well developed character.
Character development is defined as (1) the multiple sets of qualities, attitudes, traits that emerge over the course of a novel and as (2) the progression of a character from one state or condition to another improved or more successful one.
What personality traits of Mrs. Bennet do we see?
Mrs. Bennet is a multifaceted character who is critical in the development and illustration of several of Austen's themes. Of course, the first manifestation of Mrs. Bennet's personality we see is her euphoria over the appearance at Longbourn village of a marriageable bachelor, Mr. Bingley. Her adamant interest in finding five excellent marriages for her five daughters motivates her elation.
While it often supposed that this opening characterization is Mrs. Bennet's "default," baseline expression of personality, it can hardly be true that her euphoria over an eligible bachelor and her normal condition could be one and the same. Her normal deportment may continue to display her "mean understanding, little information, and uncertain temper" but with an absence in normal times of her adamant euphoria.
The second time Mrs. Bennet's temperament is shown is in her reaction to Mr. Darcy when he is observed by all at the Meryton ball: "Lizzy does not lose much by not suiting his fancy; for he is a most disagreeable, horrid man, not at all worth pleasing. So high and so conceited that there was no enduring him!" While the zeal of her deprecation of Darcy has almost the same vigor as her euphoria over Mr. Bingley's arrival at Netherfield, it shows an entirely different aspect of her psychology. Not only is she single-mindedly enthusiastic over the prospect of marriage for at least one of her daughters (which should lead to encounters with other eligible young men for her other daughters), she is quick to be adamantly against someone who offends her sensibilities.
Her lack of reasonableness, her "mean understanding," and her haste to jump to extreme conclusions provide a unifying psychological connection and predict the unifying psychological basis for upcoming elements.
The third psychological element revealed comes during her experience with clergyman and cousin, William Collins, the holder of the Longbourn estate entail. As her experience with Mr. Collins unfolds, three unique psychological elements are drawn from her: (1) confusion, guilt and rejection, (2) acceptance and readiness to be pleased, (3) apologetic determination to fight.
When Mr. Collins' visit is first introduced by Mr. Bennet on the very day of his expected arrival, Mrs. Bennet is overcome with confusion exacerbated by guilt and her sentiment deploring Collins.
But where does the confusion and guilt come from? We are told much later in Chapter 50 that she and Mr. Bennet always intended to produce a male child who would break the entailment of the property to Collins. In that belief and to that end, they squandered their wealth without setting any aside because it would all be restored by their male heir.
Yet, it was five daughters that were given birth to. Mrs. Bennet held on to the belief that she even then would produce a male child but the "event had at last been despaired of...." Mrs. Bennet believed she could do her part in breaking the entail. This is the source of the confusion and guilt that underlie Mrs. Bennet's protestations against the entail and her finding Mr. Collins deplorable.
As soon as Collins declares his intention of taking a bride from one of the five Bennet girls, Mrs. Bennet has a renewal of hope and a surge of good will toward the previously deplorable man. This, though it seems illogical at first encounter, has a logical basis in her history, for part of her anxiety over the entail is that she and her unmarried daughters will be turned out of Longbourn upon the death of Mr. Bennet since Collins would then hold the hereditary claim.
Hence when Collins offers Mrs. Bennet a solution to her most worrisome and guilt-ridden problem, she shows a psychological turn toward being completely accepting (this is probably the side Mr. Bennet first knew of her when they were happy, quick to spend and confident of a male heir) and ready to be pleased by all he utters, which is shear folly since his utterances are mere obsequiousness.
Austen subtly develops a rounded character--one with "many traits"--in Mrs. Bennet by revealing various aspects of her psychological make-up including her apologetic willingness to fight Collins' battle for him and argue Elizabeth into accepting his offer of marriage:
"But, depend upon it, Mr. Collins," [Mrs. Bennet] added, "that Lizzy shall be brought to reason. I will speak to her about it directly. She is a very headstrong, foolish girl, and does not know her own interest but I will make her know it."
One of the more telling psychological traits that Austen develops in Mrs. Bennet is brought to light in her encounter with Lady Catherine de Bourgh who invades their modest home--by comparison to Rosings--for the purpose of demanding from Elizabeth a renunciation of her rumored engagement to Mr. Darcy. Upon Lady Catherine's bursting into their sitting room, Mrs. Bennet, to whom Elizabeth whispered the name of Lady Catherine de Bourgh, was stunned and awed into silence, a remarkable condition for Mrs. Bennet. More importantly, Mrs. Bennet was stunned into the "utmost politeness.":
"Mrs. Bennet, all amazement, though flattered ... received [Lady Catherine] with the utmost politeness."
This meant in part, by the laws of social propriety, that Mrs. Bennet could not initiate conversation. She had to wait until Lady Catherine requested an introduction even though the Lady was in her home: "no request of introduction had been made." So in polite silence Mrs. Bennet sat. This didn't last long of course, and as soon as Lady Catherine provided a socially acceptable opening (though not a socially correct opening because Lady Catherine's question was addressed to Elizabeth), Mrs. Bennet began talking about her girls, beginning with inappropriate praise of Lydia, her youngest but first to marry, which is happiness to Mrs. Bennet but would have been a horror to Lady Catherine had she bothered to hear.
Mrs. Bennet is here fully developed as a round character: she has a full range of psychological characteristics that motivate different actions and reactions in differing situations, including her legitimate anguish, though dramatized for greatest impact, over Lydia's ruinous elopement with Wickham to London, with no stop in Gretna Green for a quick marriage ceremony. Still, how is Mrs. Bennet related to theme development?
Mrs. Bennet and Theme Development
Mrs. Bennet is significantly connected to the development of the themes of female education, vanity and conceit, manners associated with varying classes, marriage of daughters (especially when juxtaposed to Charlotte Lucas), along with estate entailment and the "female line": "I see no occasion for entailing estates from the female line. It was not thought necessary in Sir Lewis de Bourgh's family" (Lady Catherine). The education theme is most significantly brought out when Lady Catherine grills Elizabeth about the tutors and masters she and her sisters had, or, more correctly, did not have:
"Five daughters brought up at home without a governess! I never heard of such a thing. Your mother must have been quite a slave to your education."
Elizabeth could hardly help smiling as she assured her that had not been the case.
"Then, who taught you? who attended to you? Without a governess, you must have been neglected."
"Compared with some families, I believe we were; but such of us as wished to learn never wanted the means. We were always encouraged to read, and had all the masters that were necessary."
When Elizabeth has her eyes open to the real deficits of her family, she takes a clearer view of the disadvantages Mary, Kitty and Lydia suffered by not being submitted to a regular education.
There is little difficulty is associating Mrs. Bennet with the theme of vanity and conceit, a theme Mary at one point waxes philosophical over. We see that Mrs. Bennet's vain and conceited ideas of elevated self-importance lead to improper conduct in relation to her duties, in relation to her deportment in social settings, in relation to her hasty and inadequate judgements of other people, and in relation to her willingness to expose the family's folly to any who might listen.
A rather interesting theme with which Mrs. Bennet is connected is that of the difference of manners between the upper and lower classes. Mrs. Bennet, when single, was Miss Gardner, sister of Mr. Gardner (uncle to her daughters and partial savior of Lydia) and Mrs. Philips of Meryton. Their father was in trade, as is Mr. Gardner. Mrs. Bennet nee Miss Gardner married above her class because Mr. Bennet was an upper class gentleman of independent wealth. Though now of the upper class herself by virtue of marriage, her manners are still lower class and have been imparted to her three youngest daughters. Darcy makes a point of this when he says that Elizabeth and Jane cannot be discredited ("to have conducted yourselves so as to avoid any share of the like censure, is praise no less generally bestowed on you and your elder sister" Ch 35) and it is reinforced by Mr. Bennet's own comment to the same effect ("Wherever you and Jane are known you must be respected and valued" Ch 41).
The difference is shown also in the contrast between the Bingley sisters, the daughters of a tradesman, and Miss de Bourgh, who represents (quietly) elegant upper class manners. There is also a surprising similarity between Mrs. Bennet and Lady Catherine, also based on conceit, but of a different nature since Lady Catherine has actual authority and power to back up her conceit because of recognition in the de Bourgh family of "the female line."