At the end of stanza 1, the nightingale sings a summer song. As the speaker puts it, the bird

Singest of summer in full-throated ease

The nightingale, sitting amid the shadows, sings effortlessly.

This beautiful song mesmerizes the drowsy speaker so that he wishes he could drink it in as if it were a cool, aged wine tasting of a beautiful green country. The song causes the speaker to think of dancing and laughter and the warm southern climate of the Mediterranean countries.

The speaker wishes that through the potion of nightingale's song, he might fade away into a beautiful dream world. He is intoxicated by the music.

The nightingale's song leads the narrator into a long reverie in which he longs to cast off human consciousness so he can feel as carefree and eternal as the bird, who is not oppressed by human anxieties.