The speaker is saying that he himself is a separate person from everyone else. But everyone else is in a huge group.
He is saying that when he sings it feels like he is singing from top to toe. The brain is not worth of being independent. He is saying that he believes that without no body there is no soul. The female sings equally with the male.
Life is full of passion and power. You can be cheerful and be free under the laws. He is singing by himself but stuck in a group of people.
In the first stanza he gives you a look of a person singing alone. He gives you a look at a group of people that's around him.
In the second stanza it gives you a look of him singing from top to toe. It shows you that he doesn't think that the brain is worthy of being independent. It gives you a look of the form being complete and him singing with another person at one point.
In the third stanza it gives you a look of how passion, pulse, and power relate into you as an individual. You can be cheerful and go against the laws and be good with it. He shows you that he can be
The main images being shown is a man singing, eventually with a female. He describes being in a group of people who are the same. Eventually he figures out that he doens't have to be in the group and can be his own person