This isn’t for homework I just need an answer and I can’t find it online. Is there a topic in this sentence? “I’m going to use the bathroom” if there is a topic, would the topic be “I” or “Bathroom”?

This dust was once the manthis dust was once the man,gentle, plain, just and resolute, under whose cautious hand,against the foulest crime in history known in any land or age,was saved the union of these states walt whitman who is "the man" the dust now represents? the narrator a criminal whitman lincoln