The theme "Exploration" is easy to pick out, since the spider and the soul both explore. This theme helps us to see the more positive aspects of the poem. There is a hopeful note here, especially at the end. Eventually the spider will start his web, and the soul will make contact with something across that vast ocean. Exploration is exciting, full of promise and hope – although it can also be boring, scary, and dangerous.
By talking about the spider, and then about the soul, the poem suggests that spiritual exploration is more important than any physical trip we might take.