"By the envy of the devil, death entered the world."

Envy was the cause of Satan's fall and envy was therefore the logical means he used to tempt men to disobey God.  (It is often said that this was pride, and indeed pride is the root of all sin).  It is said that Satan was one of the angelic princes, one of those closest to God.  Who then did he envy?  God himself.  He saw God in a limited way before the angelic test after which the good angels entered into the beatific vision.  Even so, with his free will he chose to be dissatisfied with the exquisite beauty with which God endowed him and envied God's attributes.  He was already in the highest choir but he sought a high realm still:

How you are fallen from heaven,
   O Day Star, son of Dawn!
How you are cut down to the ground,
   you who laid the nations low!
You said in your heart,
   ‘I will ascend to heaven;
I will raise my throne
   above the stars of God;
I will sit on the mount of assembly
   on the heights of Zaphon;
I will ascend to the tops of the clouds,
   I will make myself like the Most High.’

In his train, with his massive power he drew a third of the other angels with him according to tradition.  We read in Jude 6 that "the angels did not keep their own position, but left their proper dwelling."  Since their proper dwelling was situated in the choir into which they were created we can surmise that they too envied the qualities of the angels in the choirs above them.  And when it was made known to them that they were prohibited from leaving their proper place and furthermore that one day God would become man and possess a human nature lower than theirs and that they would be told "Let all God's angels worship him" (Hebrews 1.6) the cry went out "we will not serve!"  So they were sent to a place where they did not have to serve or obey, in the process losing all freedom, joy, light and peace for eternity.

The angelic test came from God, man's test came from Satan since man is lower than the Angels.  It is no surprise that Satan tempted man with the same lie he crafted for himself: "you can decide for yourself what is good and evil, you can become like gods -- you should become like gods; do not fear disobedience, God is being unjust by keeping you in your place, you can become better if you want -- smarter, wiser, like God himself.  Why does he hold you back?"  Satan is the great exaggerator and Adam and Eve did not know of their limitations until Satan told them.  "Through the influence of the 'Father of lies'...man will be inclined to see in God primarily a limitation of himself, and not the source of his own freedom and the fullness of good."  (John Paul II, Dominum et Vivificantem).  Man rejects God's Word and therefore repeats the crimes of Satan.  As a punishment man will now experience death; all men and women now die as the result of Adam and Eve's sin.  "Sin came into the world through one man, death came through sin, and so death spread to all...one man's trespass led to condemnation for all."  (Romans 5.12, 5.18)

Thus we see the great evil and powerful effects of envy and ambition.  "Envy and selfish ambition are devilish," says the word (James 3.14-16).  We are warned to "do nothing from selfish ambition or conceit, but in humility regard others as better than yourselves."  (Philippians 2.3)  When St. Paul is talking about the necessary requirements of bishops to Timothy he says "they must not be recent converts or they may be puffed up with conceit and fallen into the condemnation of the devil."  (1 Timothy 3.6)

O Lord, my heart is not proud

nor haughty my eyes.

I have not gone after things too great for me

nor marvels beyond me. (Psalm 131)