John of Lycopolis said, ‘This is what it means to renounce the Devil and all his works. For through any sinful act or the onset of a perverse desire the Devil enters into our hearts, for vices are from him just as virtues are from God. So if there are vices in our heart, when their prince the Devil comes they give him room as their own creator and they introduce him to his own possessions. When this happens, such hearts can never have peace or stillness but are always thrown into disorder and held fast and oppressed, sometimes by an empty cheerfulness, sometimes by a vain sadness. For they have an evil occupant within them to whom they have given the means of entry through their passions and vices.
`On the other hand, for a mind that has truly renounced the world, that is, one that has cut off and severed itself from every vice and has left the Devil no means of entry, a mind that has checked anger, put down fury, avoided deceit, banished envy, and not only does not disparage its neighbor but does not even allow itself to think or suspect any evil of another and which takes to itself the joys of a brother and reckons his sadness as its own, a mind that observes these things and those like it, there will always grow therein the fruits of the Spirit, which are joy, happiness, love, patience, long-suffering, and goodness. This is what the Lord said in the Gospel: A good tree cannot bear bad fruit, nor can a bad tree bear good fruit.’ For a tree is known by its fruit’ .
