The theme of Percy Bysshe Shelley's lyrical ode "To a Skylark" is the power of nature to inspire and delight the human spirit.
While the poet listens to the small night bird sing with delight as it soars to the heavens, he, too, is enraptured with its "rain of melody" that showers down spontaneously:
What thou art we know not;
What is most like thee?
From rainbow clouds there flow not
Drops as bright to see
As from thy presence showers a rain of melody.
In subsequent verses, the poet seeks to compare this delightful bird's song that generates images of maidens, sweet-smelling roses, the gentle sounds of rain, and much more, to the wonders of the heart. And, yet, the poet wonders how this blithe spirit can know such happiness without having experienced sorrow: "Thou lovest—but ne'er knew love's sad satiety." For people's happiness is relative to the sorrow that they have experienced.
Finally, the poet calls upon the skylark to teach him such pure joy as it has because if he were to possess this pure happiness, the world might listen, just as he is listening now to the lovely songs of this bird.