Metaphor

In the poem, Toads, a toad is used as a metaphor to describe work. Now everyone one of us that work have reasons to not like it, but would you compare it to a toad? Why would you go as far to comparing a job to an amphibious animal? A good comparison that I liked is : "Six days of the week it soils, with its sickening poison, just for paying a few bills!" Many times we go to work just for the money. And the toad(work) is poisining our lives. This poem is definitely full of comparisons, and I probably have missed a lot of them while reading it.