Repetition is a huge part of this poem’s style. Words, phrases, and sounds all come rolling in again and again. To us, it sounds a little like waves rolling in on a beach. They are repetitive, evenly spaced, but also a little mysterious – maybe a little wild and dangerous sounding. When you look at the ocean, you might get a feeling of "vacant vast surrounding." Whitman even helps us out by talking about "measureless oceans."
But, there’s more. Read the poem aloud; listen to the sounds that it makes. When you hear "filament, filament, filament" (line 4), you might hear quiet little waves lapping at the shore. In the last two lines, the waves build and come crashing in, one after the other: "Till the bridge… till the ductile anchor… till the gossamer thread" (lines 9-10). Simple repetitions, but they grow together into something more profound. These wave sounds give you the feel of the immense empty space that Whitman wants you to imagine. The repetition of the waves is infinite and beyond our control, and that’s a lot like the work of the spider and the movements of the soul in this poem.