The devil converses with a person without using a voice, yet with words; because thoughts are the same as words, only not uttered by a voice, not clothed in sounds without which men cannot communicate their thoughts to each other. In the same word, Makarios the Great says, “The devil acts so cunningly that all evil appears to us as if it were born of itself in the soul and not from the extraneous action of an alien spirit acting maliciously and endeavoring to remain hidden.”
~Ignatius Brianchaninov
Prayerful Life 