In the quoted lines from canto 3 of Childe Harold’s Pilgrimage, the speaker is reflecting on the pluses and minuses of living a creative life. On the one hand, creativity increases the intensity of the creative person, while on the other hand, it also robs them of their identity. Once a creative work is completed, it takes on a concrete reality of its own. The person who made it is merely a vehicle for it to come into existence. In previous stanzas, he had addressed his daughter. This stanza merges the idea of a person’s actual, physical child with that of their creative offspring—in his case, poetry.
Lord Byron uses apostrophe as the speaker directly addresses the “soul of my thought.” This speaker, whether representing Harold or Byron himself, is reflecting on the lack of identity of the creative person—especially a poet. Using a rhetorical question—“What am I?”—he conveys this absence of identity with the response, “Nothing.” His thoughts of his child or his creative work serves as his constant companion wherever he goes. He feels this creativity looking back at him, “invisible but gazing.” The father and the child, or the poet and his poetry, are mixed together. Reflecting on these ideas makes him realize how limited or inadequate his own feelings are.