But interwoven with this contrast is the theme of secrecy and sickness which too is conspicuous. Secrecy and sickness have inseparably been interconnected with the characters of Elinor and Marianne; and this theme is interconnected with their lives, with the lives of the other characters, and with the life of society as a whole.
The critic, who has pointed out secrecy and sickness as being a dominant theme of the novel quotes a remark made by Mrs. Jennings. That remark is: "Come, come. Let's have no secrets among friends". This remark according to our critic acquires additional significance when we consider just how much secrecy there is among the few, closely-related characters in the book. Colonel Brandon suddenly departs from Barton Park, thus unsettling a planned visit to a beauty spot, but he does not give any explanation for his departure. In other words, he keeps the reason for his sudden departure a secret from everybody.
Lucy reveals to Elinor her secret engagement to Edward Ferrar, but she reveals it only to Elinor, and she does so in order to silence Elinor as her potential rival. Lucy does not tell this secret to anybody else: and to Elinor she clearly says that this engagement had always been intended to be kept as secret. Willoughby's unaccountably cruel conduct towards Marianne is due to his secret plan to marry some rich heiress, though the plan remains no longer a secret when it becomes known that he is going to marry Sophia Grey. Concealment obviously suits the calculating designs of these two self-seekers, namely Lucy and Willoughby.
But there are more secrets in the part of main eligible males in the novel. The good-hearted but insensitive Sir John Middleton goes out of his way to create secrets in order to bring a somewhat vulgar spiciness to his dinner-table. "His name is Ferrar." says Sir John in a very audible whisper, "but pray do not tell it, for it's a great secret." We can imagine that the motive behind this kind of social mockery was the same as the motive behind the masked ball. If a society finds itself too utterly transparent and everybody too boringly familiar, it may well seek to introduce some shadows, masks, and screens if only to restore the stimulus and emotional thrill of a rudimentary sense of mystery—or at least, the titillating atmosphere of erotic conspiracy.
But there is a much more important kind of secrecy of which Jane Austen makes us aware. This is the secrecy of those things within human beings which are struggling to get out but which encounter different kinds of restraint or suppression. A striking example is the extraordinary silence and strange kind of secrecy maintained by Marianne and Willoughby during the period of their friendship as long as Willoughby lives at Allenham; and later, in London, Marianne is secretive even towards Elinor, manifesting a privacy that escapes all Elinor's watchfulness. Elinor herself, on hearing of Lucy's engagement to Edward, manages "a composure of voice under which was concealed an emotion and distress beyond anything she had ever felt before." The phrase "the necessity of concealing" which occurs in context gives some indication of Elinor's sense of responsibility towards code of formal behavior; as a result no one would suppose "that Elinor was mourning in secret over obstacles which must divide her forever from the object of her love."
The secrets do not end here. When Colonel Brandon seeks confirmation from Elinor that his love for Marianne cannot be reciprocated, he feels that "concealment, if concealment be possible, is all that remains." The recurrence of such phrases as "ill-judged secrecy", "the appearance of secrecy", and "promise of secrecy" suggests how prevalent is the vocabulary of all kinds of concealing, whether the sets are those kept by the individual from society, or those which one's private self must try to keep from one's public self. Elinor, who becomes the repository of other people's secrets without there being anyone to whom can tell her own, experiences in full the burden and the torments of secrecy. She tells Marianne on one occasion that for four months she has been having many things "hanging on her mind" without being at liberty to speak of them to anybody. And if silence is often required in the interests of honor and dignity, there may be another justification for secrecy, sometime more like self-survival. This is hinted at in the revealing letter written by John Dashwood to Elinor, after Lucy has got secretly married to Robert Ferrars. In that letter, John Dashwood writes that the secrecy, with which the marriage was performed, had been treated by Mrs. Ferrars as enormously annoying Robert's crime because, if any suspicion of it had occurred to anybody, proper measures would have been taken to prevent the marriage. In this case nobody would suppose that the scheming Lucy had married for love; but the wording of John Dashwood's letter hints at the cruel, coercive powers of society and the ruthlessness with which many people were willing to manipulate or to rectify the deviations of individual passion in the interests of wealth or some illusory property. So if secrecy is often a painful obligation imposed by the formal requirements of a rigid society, it may also be a strategy against or around them.
By the end of the novel, all the secrets have come to the surface. Marianne is a person who believes in letting the emotions use the body as an expressive medium of expression. It is therefore, not surprising that she indulges in shedding tears as often as Elinor strives to maintain her composure. But what happens after Willoughby first departs from Allenham and Barton, and subsequently treats her with an incomprehensible cruelty, goes beyond the behavior of an emotional girl. Jane Austen describes Marianne's illness in such detail that we get some idea of the language of symptomatology and diagnosis of her time. Marianne suffers from melancholy; she gets headaches, experiences low spirits, and feels quickly tired. Some people of the time would even think that she had lost her mind and was approaching insanity. But the important fact, which emerges from her illness, is that her illness is at least partly due to the rigors of the social code. Of course, she is sick because of the intensity of her own secret passions and fantasies; but her sickness also partly shows that the society of the time was completely dominated by "forms" or "screens" which might, in turn, be lies. Marianne looks upon forms as being mostly lies; and so she refuses to collaborate with society in keeping up the forms. Society is for her as trivial as the endless game of cards which others take delight in playing. Characteristically, she would never learn that game. Society is maintained by lies which it thinks to be necessary; but Marianne is unable to cooperate with society in the upkeep of forms and in the resort to lies; and it is her inability to cooperate with society, and the consequent strain upon her mind, which cause her to fall gravely ill.
The inevitable inference, which we can draw from all this, is that society would itself become diseased if its members habitually maintain secrecy about certain things in their lives and if they insist on certain outward forms being preserved. In other words, secrecy itself can lead to sickness. And yet, as long as society insists on the observance of forms and therefore the resort to falsehood and to lies, the individual who refuses to go along the path laid down by society, would suffer the disastrous consequences of his or her non-compliance. In short, society is, for all practical purposes, a tyrannical overlord who, without formulating its wishes and demands into an explicit code, commands the faithfulness of a large majority of its members, making the dissidents and the rebels pay the penalty of their non-conformity.