I looked up the title and found about 10 different poems, so I decided to explain metaphors to you instead. Metaphors are figures of speech that compare two unlike things and use the words "is" or "was". So, if you said, "He is a pig," then that would be a metaphor. If you said, "He eats like a pig," then that would be a simile which is also a figure of speech. When reading poems, look for two ideas or things being compared to each other that wouldn't be natural and find the word that connects them. If it is an "is" then you've found a metaphor. Writers do this in order to get their points across with ideas and things that are more understandable from the physical world or from emotions that most everyone can relate with. If you can't relate to a metaphor, try looking up the words that are associated with it to bring more understanding.