The rustling darkness in the sleepy wood Glides toward the water to quench its thirst, Studies the tracks where a deer has stood, Then crosses the beach in an eager burst.
The waters ripple as Night drinks her fill. Stars fall on the lake from her blue-black hair. She lingers, dreaming, as the air grows chill, Then gathering her jewels, she returns to her lair.
Night, in "Nocturne," is not a time of day but a creature, a woman who slips out of the woods, drinks from a lake, and slips back again. The first stanza follows her approach: the darkness glides through the trees, pauses over a deer's tracks as if curious, then rushes across the beach toward the water. In the second, she drinks, and the ripples spread. Stars fall from her "blue-black hair" and scatter across the surface, which is a lovely way of describing their reflections shimmering on the lake. Then she lingers, dreaming, until the air turns cold, collects her "jewels" (the stars again) and goes home to her lair.
The speaker never says how they feel, but the tone gives it away. They watch quietly and with real tenderness, as though lucky to have witnessed something private. The mood is hushed, dreamy, and a little wild, part lullaby, part fairy tale.