What metaphors are used in Having it Out with Melancholy by Jane Kenyon?

The fourth section, titled "Often," comes closest to pathos in this poem, particularly the first three lines. The speaker lets the reader know she wants to be "adult" and "try to wait for dark" to go to bed when apparently she feels like going to bed much sooner. However, she is rescued from total self-pity in the final three lines, if by no other means than a nice metaphor. Sleep is a sanctuary for the speaker and she likens it to a "coracle," or a small boat made of waterproof material stretched over a wicker or wooden frame. In the coracle she can "push away / from the massive pain" of mental illness the same way one would push a small craft away from a troubling shore.