The Transformation from Genesis B:
"Then Almighty God, High Lord of heaven, was filled
with wrath, and hurled him from his lofty throne.
He
had gained his Master's hate, and lost His favor.
God's
heart was hardened against him. Wherefore he needs
must sink into the pit of torment because he strove against
the Lord of heaven. He banished him from grace
and
cast him into hell, into the deep abyss where he became
a devil. The Fiend and all his followers fell from
heaven;
three nights and days the angels fell from heaven to
hell.
God changed them all to devils."
-taken from part VI, lines 299-310.