Read this excerpt from “Going Back to School.”

The sky was like a cup some rare wine fills,
And stars came as he watched
– and he was free
One splendid instant – back in the great room,
Curled in a chair with all of them beside
And the whole world a rush of happy voices,
With laughter beating in a clamorous tide. . . .
Saw once again the heat of harvest fume
Up to the empty sky in threads like glass,
And ran, and was a part of what rejoices

Which part of nature does the poet reference more than once to express the speaker’s feeling of freedom?

the sky
the tide
the stars
the harvest