Conversation so far:
Is Leaves of Grass by Walt Whitman a poem?
Leaves of Grass is a poetry collection by the American poet Walt Whitman.
When did Walt Whitman first writing Leaves of Grass?
As early as 1850, Walt Whitman began writing what would become Leaves of Grass.

Question: What are some of the subject matters of Leaves of Grass?
Self-contained rewrite: What are some of the subject matters of Leaves of Grass by Walt Whitman?