Answer: The comparison between the human heart and the setting sun.
Step-by-step explanation:
"A Hymn to the Evening" is a poem by Phillis Wheatley, an African American poet who ended up as a slave when she was only 12 years old.
The speaker in the poem compares the human heart to the beautiful sunset. She is convinced that this stunning sunset was created by God. Therefore, she wants to show her love for God by taking on the "glow" of the evening sunset. The poem was written based on her own experience as a slave. She would work during the whole day. In the evening, she would be allowed to rest, which explains the positive connotation of the sunset in this poem.