He is called Satan, because he is an enemy to God, (for this the Hebrew word signifies,) but he is called the Devil, because he assists us in doing evil, and is an accuser. His nature is incorporeal, his abode in the air.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Hom. Quod Deus non est auctor mali.
