What is the central idea of this poem o captain my captain

The poem is an elegy to the speaker's recently deceased Captain, at once celebrating the safe and successful return of their ship and mourning the loss of its great leader. In the first stanza, the speaker expresses his relief that the ship has reached its home port at last and describes hearing people cheering. Despite the celebrations on land and the successful voyage, the speaker reveals that his Captain's dead body is lying on the deck. In the second stanza, the speaker implores the Captain to "rise up and hear the bells," wishing the dead man could witness the elation. Everyone adored the captain, and the speaker admits that his death feels like a horrible dream. In the final stanza, the speaker juxtaposes his feelings of mourning and pride.