The metaphor selected by the Vicomte de Valmont for his latest exploits in love (Letter Twenty-one) is one of travel. He congratulates himself on being "on the right road" ("dans la route"), having made progress, "a step forward" ("un pas en avant"). This metaphor is drawn from the story he relates about being followed on his way to the village and having to choose a path. The repetition of the motif of travel is not only an indicator of how Valmont may view love, but also an indicator of his writing skill. His words do not fall this way by accident. They are seamless and confident. They form not only a good style, but also an excellent armor against Merteuil.
In fact, Valmont uses this kind of repetition of motifs throughout his writing. Tourvel's religious tones begin to appear in his letters. The Vicomte adopts the Présidente's language to convince her, but this also tends to alter what he says. Therefore, he must subvert Tourvel's religious motifs to his own purpose with parody, just as he must subvert her religious convictions.
Religious motifs surround Tourvel. She is often described as praying, or as having the air of prayer about her. Her letters are also full of religious imagery. Valmont's first love letter to her (Letter XXIV) is a pledge to renounce his desire. He asks a series of questions, not unlike a catechism, which culminate in a prayer that she, like a deity, give him her "generous care" ("soins généreux"). He has just used a Christian style of argument to convince Tourvel that she should continue to associate with him, and continue to allow herself to be seduced by him.
For whatever reason, Tourvel is persuaded enough by Valmont's pleas to reply to him—perhaps his appeal to her charity convinces her. But she is smart enough to try to put a greater amount of distance between the two of them. She even attempts to erase the entire incident: returning Valmont's letter and asking that he in turn return hers. Her strongest defense seems to be to pretend that nothing at all occurred between her and Valmont. Having denial as her only weapon may put her in harm's way, since, by continuing to fight adamantly against Valmont's claims, she also confirms the danger and significance of these claims.