Final answer:
The line 'like a doorless cage' in the poem is an example of a simile.
Step-by-step explanation:
The line 'like a doorless cage' is an example of a simile, which is a figure of speech that compares two unlike things using 'like' or 'as'. In the given line, the poet is comparing the line to a doorless cage to convey a sense of confinement or restriction. This comparison helps to create a vivid image in the reader's mind and contributes to the overall theme and mood of the poem.
Learn more about Types of figurative language