SELF is the sense of being of all creatures. It is a being's perception of its essence, reason, and importance. Self naturally is proud, selfish, and often brutish, it sees itself as better than every other, it does not want to submit, sacrifice, or love except for itself, all it ever wants is to receive and not to give.

The understanding of self is inherent in every being, and so also is the perception of God.

Before the creation of the earth and the advent of man, every thing and being in heaven only had one preoccupation, the worship of God. And as they lived in obedience, they occupied their place and space, which in essence is their relevance, purpose and glory. But when a few disobeyed, they lost their place and space; they became disconnected from the life of God, and were cast out of Heaven.

“I ordained and anointed you as the mighty angelic guardian. You had access to the holy mountain of God and walked among the stones of fire. “You were blameless in all you did from the day you were created until evil was found in you. Your rich commerce led you to violence, and you sinned. So I banished you in disgrace from the mountain of God. I expelled you, O mighty guardian, from your place among the stones of fire.”
‭‭- Ezekiel‬ ‭28‬:‭14‬-‭16‬ ‭NLT

“How art thou fallen from heaven, O Lucifer, son of the morning! how art thou cut down to the ground, which didst weaken the nations! For thou hast said in thine heart, I will ascend into heaven, I will exalt my throne above the stars of God: I will sit also upon the mount of the congregation, in the sides of the north: I will ascend above the heights of the clouds; I will be like the most High. Yet thou shalt be brought down to hell, to the sides of the pit.”
‭‭- Isaiah‬ ‭14‬:‭12‬-‭15‬ ‭KJV‬‬

In essence whenever self is not consciously seeking God, it is actually exulting itself against God. Everything created is for His worship, and worship always keeps humble, strengthens, beautifies, makes rich, and gives life.

Purpose defines the essence of every creature; ANYTHING THAT DOES NOT CONSCIOUSLY GLORIFY GOD CUTS ITSELF OFF IT'S LIFE SOURCE AND THUS BECOMES IRRELEVANT AND NEEDLESS in the grand scheme of things.

The preeminence of "self" is the only undoing of Satan, and also becomes that of every man that will not consciously seek and worship God.
This is the cardinal sin.