Wait, what's a catalogue? In poetry, catalogue is just a list of stuff. It could even be a grocery list, provided you've got especially poetic groceries. "Song of Myself" is the ultimate poem for catalogues. There are just so many of them, and they go on forever. For example, Section 33 is a huge catalogue of places that his soul travels to. If you're trying to figure out just what makes Whitman so distinctive, this technique is a great place to start.