We begin Book IV with Satan as he looks in on the Garden of Eden and God's new favorites, Adam and Eve. This inner dialogue presents us with an interesting view of Satan's thoughts and feelings at a very critical moment in the tale. It is here where we realize that Satan knows exactly what he is doing. It is here where he makes his final decision to act against good and willfully walk in evil. Satan's motivation is a naked ambition for power. He desires the power that God possess and if he cannot possess God's power in heaven he decides that he must have power over earth or at least ruin God's demonstration of power through earth and humanity.
Indeed, Satan's dialogue focuses almost solely on power and his quest to gain it. The dichotomy or binary opposition of power versus subjection is described continuously in these lines through the analogy of height versus depth. .
Throughout the course of history, the association of height with power and depth with subjection has been one of the most basic symbolic interactions of humanity. Kings have traditionally sat on raised platforms to enhance their psychological presence in a room while subjects were not only forced to stand below the king, but were also made to bow. In fact, many cultural royal traditions made it a criminal offense for a person to raise his head above that of the king in his presence.
This perception of height portraying power stems directly from another of man's most traditional pastimes, that of warfare. The castles of Europe occupy the most scenic terrain of the continent for one reason, the most scenic views are from above and being above offers the greatest strategic advantage in warfare. "High ground" has traditionally been one of the most important deciding factors in warfare. In Milton's day high ground was important in warfare for very practical reasons. Height provided the advantage of a better view of the battle.