I felt myself falling Down a chasm wide and deep, Through darkness and silence As soft and smooth as silk, Till I heard birds calling In a drowsy world of sleep, And stood with flowers blowing By fountains white as milk.
Falling asleep is usually described as drifting off, but here it begins with a drop. The speaker feels themselves tumbling down a wide, deep chasm, which sounds like it should be frightening. Yet the fall is oddly gentle. The darkness is silent, and the poet compares it to silk, so the whole descent feels smooth and cushioned rather than dangerous.
Then the scene changes. Bird calls reach the speaker, and the fall ends in what the poem calls a "drowsy world of sleep." It's a small garden-like place with flowers swaying in the breeze and fountains "white as milk." The images are simple, bright, and calming, a sharp contrast with the dark chasm before.
The mood is peaceful and dreamlike. The poem suggests that sleep, which might seem like a loss of control, is actually a safe passage into something beautiful. The steady rhythm and soft sounds of the words help you feel that slow, sinking comfort yourself.