Act I takes place against the backdrop of a Rococo tapestry, a representation of François Boucher's "Triumph of Love" (1754). The "Triumph" allegorizes the victory of love over power: Venus points to Vulcan's conquered heart, and the god gazes up at her like a love-sick boy.
Though the most obvious reading might consider the tapestry as prefiguring the defeat of Mrs. Cheveley and reconciliation of the play's lovers, the significance of the allegory is not so self-evident. Indeed, it takes on a number of meanings. In the story the tapestry tells, Venus conquers Vulcan only to commit adultery with his brother, Ares. In this sense, Love's triumph is more Mrs. Cheveley's than the Chilterns', the former having similarly betrayed Lord Goring in their youth.
Within the action of the play itself, the tapestry takes center stage, so to speak, at the end of Act I, when the audience has just witnessed an argument that appears to foretell the doom of the Chilterns' marriage. Horrified, Sir Robert sits in the dark, the tapestry left lit by the chandelier. In this case then, the image of Love's victory is ironic as it would seem that intrigue is poised to ruin conjugal bliss.
We can chart one more mention of the Boucher tapestry in Act II. Telling Lady Chiltern of her plans for the day, Mabel will jest about standing on her head while playing tableau in the "[t]riumph of something." This joke perhaps prefigures Mabel's own turning of love upside-down in her rather unconventional courtship with Lord Goring: recall that Goring and Mabel resist notions of love as duty and dispense with the questions of ideal marital life that consume the Chilterns.
The play's other notable symbol is Mrs. Cheveley's diamond brooch. Like the tapestry, it takes on multiple meanings through the course of the play. First, as a diamond snake, it symbolizes the evil woman—a woman who resembles a skin-shedding reptile in her duplicity.
The brooch also functions as an agent of vengeance. Ultimately revealed as a wedding gift Mrs. Cheveley stole in her youth, the brooch returns as evidence of a past crime, entrapping a woman who would manipulate past wrongs to her own advantage and wreck marriages. The "poetic justice" in her arrest is clear.