I expect you to be sincere and as an honourable man never to utter a single word that you don't really mean.
Uttered by Alceste in the opening scene of The Misanthrope, this line quickly establishes Alceste's extreme value system. His expectation that Philinte never say a single dishonest word is somewhat of a ridiculous request; we immediately recognize that Alceste will be impossible to please. Alceste's comment seems especially extreme juxtaposed with Philinte's rational defense of the practice of occasionally bending the truth. With this quotation, then, Molière establishes the central conflict of the play—Alceste's unwillingness to forgive the faults of his fellow man. Molière also defines Alceste's supposition that he somehow carries higher status than his acquaintances. Alceste expects Philinte to behave a certain way—implying that Philinte has an obligation to do so.
Additionally, this line helps set the comic tone of the play. Departing from his earlier comedies, Molière focuses his satire on human behavior rather than attacking larger classes and social system. Alceste is not the typical farcical stereotype, but he does represent extreme values. In this sense, he is the caricature of a prudish grump. Over the course of the play, Molière dissolves this particular image of Alceste, but it never disappears completely.