Who asks Whitman what a blade of grass is?

In Walt Whitman's poem "Song of Myself," the speaker, who is often understood to be Whitman himself, asks himself the question "What is a blade of grass?"

The question is not addressed to another individual but is a reflection of the speaker's wonder and fascination with the natural world. The poem explores the vastness and interconnectedness of life through the seemingly simple image of a blade of grass.