Symbolism, Imagery, Allegory
When Claude Anet, Mme de Warens's love, unexpectedly dies, we thought Rousseau would be thrilled. Okay, okay—so maybe he's not that callous. But the lady he's totally devoted to is now free as a bird. In reality, Rousseau has some complicated feelings about death.
During a deep conversation with Mme de Warens, Rousseau can't help but mention that he'd like one of Claude's possessions: a "fine black coat which had caught my fancy" (5.1.47). He's not trying to be rude—he just likes the coat.
Unfortunately, Rousseau's stupid comment makes Mme de Warens cry. Rousseau gets the picture: a coat isn't just a coat. Rousseau might not be particularly upset that Claude is dead, but he cares about Mme de Warens's happiness.
You Can't Just Take the Coat
On one hand, the coat incident helps Rousseau realize the necessity of compassion. On the other hand, he sees plain and clear how important Claude was to Mme de Warens. He can't just put on the coat and be Claude. This realization makes it (a little) easier for Rousseau to move on when it's clear that Mme de Warens isn't his one and only.