Quiet is easy to demand and hard to deliver. In this single line, the speaker admits that someone has told them to stay silent, and they have done what was asked, at least on the outside. But inside, nothing has settled. Thoughts are still running, and the word "yet" suggests the speaker knows this restlessness isn't finished.
The feeling is a mix of frustration and stubborn aliveness. We don't know who gave the order or why, and the poem never says, which leaves the instruction hanging over the speaker like a closed door. The contrast is the heart of it: a silent mouth and a noisy mind. The mood is tense but contained, like someone holding their breath while a lot is going on beneath the surface. Because the line is so short, the pause after it feels important. We're left in that silence, aware that something unspoken is still pressing to get out.