Whitman wanted to express that America is a country constituted by several parts that make a whole that works well. Each individ
ual of the country doing their part is what forms the nation. A choir is a group of people in which each one has a part to sing that might not be special on their own but form a harmony when they are sung together,
by beginning each line with the same word by ending each line with a type of worker by beginning each line with a type of worker by ending each line with the same word