<span>because it takes self-discipline and responsibility. Both of them are basically not good.</span><span />
Whitman wanted to express that America is a country constituted by several parts that make a whole that works well. Each individual 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,
