This is an example of an Epic Simile. Also known as Homeric Simile, it is an extended version of a simile, but often taking several lines. It is more typically found in poetry as a way to emphasize heroism, turning it into an unmissable feat.
A simile is a figure of speech that compares two entities, usually with the use of words like "as" or "like". For example: <em>"Your cousin is agile like a cat."</em>
The analogy is meant to show parallels between two sets of words. Fertile is to arable as vague is to clouded. If you understand either pair it can be used to decipher the meaning of the other pair you don't know.
