Final answer:
The line that contains a metaphor is 'And draws the sable curtains of the night.'
Step-by-step explanation:
The line from 'A Hymn to the Evening' that contains a metaphor is:
'And draws the sable curtains of the night.'
In this line, the evening is being compared to a person drawing curtains. The metaphor helps create a visual image of the darkness descending with the falling night.
Learn more about Metaphors in poetry