These lines from Shakespeare's play, The Merchant of Venice, embody the Renaissance concept of the music of the spheres. The idea was a poetic reworking of others, conceived centuries earlier by the Greek philosopher, Pythagoras.
Shakespeare's concept is simple. The planets observed in the night sky are engaged in a great dance. Each sings as it moves, glorifying God and joining with the choirs of angels. Human beings hold this harmony in their souls. While the soul is within the body, however, it cannot hear the heavenly music.