"If one looks at a sinner's inward disposition and outward state then it will be found that sometimes he knows much, but is blind with regards to the works of God and the matters of his salvation. It will be evident that though he is incessantly troubled, he is not active with respect to the establishment of his salvation. Even though he experiences alarm or delight in his heart, he is completely insensitive and dead to everything that is spiritual. In this regard, all the faculties of our being are injured by sin, and a sinner is characterized by blindness, negligence, and deadness. He does not see his state, and that is why he is not aware of the danger of his state. He is not aware of his danger, and that is why he does not care to rid himself of it. It does not even occur to him that he must change and work out his salvation. He is in the firm belief, which nothing can shake, that he is in a good state and on the right way, so he does not wish for anything else, and he works so that everything should remain as it is. That is why he considers any reminder about another way of life as unnecessary for himself. He does not listen to these reminders and cannot even understand what they are for - he avoids and flees from them."
- St. Theophan the Recluse, Turning the Heart to God, p.10 (published separately, this is the second part of The Path to Salvation).