There was your mistake. There was your error. The error all women commit. Why can't you women love us, faults and all? Why do you place us on monstrous pedestals? We have all feet of clay, women as well as men; but when we men love women, we love them knowing their weaknesses, their follies, their imperfections, love them all the more, it may be, for that reason. It is not the perfect, but the imperfect, who have need of love. It is when we are wounded by our own hands, or by the hands of others, that love should come to cure us—else what else is love at all? All sins, except a sin against itself, Love should forgive. All lives, save loveless lives, true Love should pardon.
Sir Robert makes this speech to Lady Chiltern at the end of Act II when Mrs. Cheveley reveals his secret past to the Lady and the latter rejects Sir Robert in horror. It is a melodramatic speech, drawn from the popular stage of Wilde's day; in this sense, it is conventional in both content and style. A key passage in the play's treatment of the theme of marriage, it establishes a difference between masculine love, which allows for or is even predicated on imperfection, and feminine love, which mounts the lover on "monstrous pedestals" for worship. As it is directed toward imperfect—and not ideal—beings, one might consider this masculine form of love as more "human." For Sir Robert, masculine love is love in its proper form, love that can cure the lover's wounds and forgive his sins.
Of course, the play ultimately does not assign this form of love to the man. Sir Robert's speech is less a description of "masculine love" than an injunction to his wife. With the reconciliation of the Chilterns in Act IV, the play will conclude that it is actually the woman's role to forgive and nurture her husband in affairs of love, thus reaffirming a familiar model of Victorian womanhood. As Lord Goring will tell Lady Chiltern in the final moments of the play, "Pardon, not punishment, is [women's] mission." Stylistically, Sir Robert's outburst exemplifies Wilde's use of melodramatic speech, a type of speech that dramatically departs his use of banter and repartee. Note the typical devices: the anaphoric sentence structure ("There was your mistake. There was your error."), antitheses (perfect/imperfect), and exhortations that build from the one previous. Such devices function to increase the pathos of Sir Robert's tirade, showing him overcome with emotion.
Perhaps most important stylistically, however, is the speech's tone. Notably, Sir Robert breaks into more epigrammatic prose in the latter half of the passage ("All sins, except a sin against itself, Love should forgive. All lives, save loveless lives, true Love should pardon."). Such epigrams use the same rhetorical structures (reversals, antitheses, etc.) that make up Wildean banter; as a result, one could, for example, imagine these lines being spoken ironically at a dinner party. Sir Robert's desperate tone—and the crisis at hand, of course—completely changes how his speech is received, stirring the spectator with a surfeit of pathos and emotion.