Orgon's son Damis is raving because he has just heard of his father's plan to force Mariane to marry Tartuffe. He tells Dorine that he is determined to expose Tartuffe as a hypocritical scoundrel. Dorine wants Damis to calm down because she has already arranged for Orgon's wife, Elmire, to talk with Tartuffe, and she furthermore believes that Tartuffe is very much taken with Elmire's charms. The hot-tempered Damis is determined to hear the conference, and when Dorine cannot get rid of him, she hides him in the closet when she hears Tartuffe coming.
Tartuffe arrives, spouting forth pious comments, and when he sees Dorine he will not look at her until she takes his handkerchief and covers her bosom with it because "the flesh is weak" and cannot withstand too many temptations. Dorine tells him that she could see him completely naked and not have any unclean thoughts. She then announces that Elmire is coming and she excuses herself.
As was noted in the preceding act, Mariane represents the simple, sweet, demure, and obedient daughter. In contrast, we see that the son represents the typical hot-tempered young man whose anger interferes with the trap being set for Tartuffe.
In this opening scene, Dorine is seen setting her plan into motion. As the wise and observant maid, she has noted that in the past Tartuffe seemed smitten with Elmire, and she now feels that Elmire might be able to persuade Tartuffe to reject the proposed marriage. Dorine, then, sets the plan in motion without having any idea that Tartuffe will later trap himself by his infatuation with Elmire. In other words, even though Dorine is responsible for beginning the revelation, not even she is aware of the exact nature of events about to occur.
When Damis hides in the closet to listen to the conversation between Elmire and Tartuffe, Molière is using one of the oldest devices in the theater; that is, the idea of having a person concealed and listening to some type of revelation. This same technique will become the method later by which Orgon is awakened to Tartuffe's hypocrisy.
Scene 2 presents the arrival of Tartuffe. The reader should be aware that Molière has held off presenting this central character until the third act. This is technically called "the delayed emergence." We have now heard about Tartuffe from all sorts of people and we have been anticipating his appearance. Now his actual arrival lives up to our expectations. He walks onto the stage spewing out pious clichés and announcing his intentions very loudly for Dorine and anyone else to hear. His opening remark, "Hang up my hairshirt" sets the tone for his character, in that a hairshirt would be the apparel of penance which a person would never reveal if he actually wore one. Thus when Tartuffe loudly announces that his is to be hung up, we are immediately aware of his hypocritical nature.
As a historical note, when Tartuffe asks Dorine to cover her bosom, and earlier when he loudly proclaims that he is going to the prison to share his money with the prisoners, Tartuffe reveals that he is aligned with a group called The Company of the Holy Sacrament, which undertook to help prisoners and which acted as self-appointed critic of women's dress. The audience in Molière's day would immediately have associated Tartuffe with this organization. And this brotherhood was instrumental in getting the play banned in 1664 and constantly strove to keep it from being produced.
Dramatically, Tartuffe's admonition to Dorine suggests that he is aware of lustful instincts and thus prepares us to accept his downfall because of his lustful desires for Elmire. Dorine's witty repartee places her as the sensible one who sees through Tartuffe's affectations and who understands now that Elmire will have some influence over him.