Walt Whitman wants to tell us that humans have become complicated and false. They have forgotten their true nature. They want to earn more and more, so that they can own more and more luxurious commodities. They do sins in order to earn then they repent. Their S sins have made them restless. Humans trouble their companions discussing their duties to God. On the other hand, animals are free from all S types of trivial anxieties, so they are still living ( their natural life.
