Ironically, one of, if not the, most powerful speakers in Paradise Lost is the leader of the fallen angels, Satan. In fact, if he were a motivational speaker in the 21stC, he most likely would command very high prices for his speeches.
Satan, who was once one of God's principal angels, rebels against God because God has given precedence to Christ, and Satan's anger takes the form of a rebellion in which he convinces a substantial number of other angels to join him. His Latin name, Lucifer, means "Light giver," which places him perpetually in the perpetually ambiguous position of having an original name with the positive connotation of "knowledge giver" but who is also know as Satan, the adversary, the devil.
Satan's motivational skills are stunningly good, so good, in fact, that Milton ultimately takes them away in Book X, but at the beginning of the struggle between God and Satan, Satan is depicted as strong, proud (to a fault, of course), articulate, and intelligent.
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