What are some examples of metaphors and symbolism in "The Brain is Wider Than The Sky"?

This excellent poem from Dickinson compares the brain to a
number of different objects and argues that the brain always comes out of the comparison
more favourably. The series of metaphors that begins each comparison each compares the
brain to, respectively, the sky, the sea and the "weight of God." However, the brain is
shown, with typical Dickinson logic, to be "wider than the sky" because of the way that
the brain can include the sky in its imaginings. Likewise, the brain is "deeper than the
sea," because it can in its imaginings absorb the sea into its being. Lastly, the brain
is exactly the "weight of God," because the brain is divine in its ability to dream,
imagine, and comprehend. This poem therefore uses metaphors to celebrate the brain and
its abilities to comprehend, dream up and imagine.