The speaker speaks directly to a forest, warning the trees that they are not as private as they think. The brook, the breeze, the lake, and even a few wakeful birds can overhear the wood’s sleep-talk. There is an intimate, almost fairy-tale atmosphere: nature is alive, listening, and full of quiet motion.
The emotional shift comes in the last line, when the speaker says, “Green, garrulous wood, I trusted you so!” It becomes clear that this is about a secret shared with the trees—one that the wood may now be murmuring to the surrounding world. The mood is tender but uneasy, mixing affection for the forest with the sting of betrayal. What felt like a safe confidant has turned into a gossip, and the speaker is left feeling exposed and wistful.