Why do demons want to work up within us gluttony, sexual immorality, greed, anger, grudges, and the other compulsions? So that the mind would grow dull by them and thence unable carry out its prayer as it ought. After all, when the compulsions of the irrational part of the soul are in charge, they do not allow the mind to be moved in accordance with reason and to seek eagerly the God who is himself Rationality and Word.
We pursue virtues so that we may grasp the rational principles of the natural world, and pursue these so that we may grasp the Word who is himself rationality. Now it is precisely in the state of prayer that he likes to reveal himself.