By St. Tikhon of Zadonsk
Whatever physical darkness is for the eyes, so is sin for the human soul. The spiritual darkness so darkens and blinds the eyes of the soul, that the sinner walks like the blind: he doesn't know where the path leads him; he doesn't see before him the torment of an eternal death in which he might fall; he doesn't distinguish vice from virtue, evil from good, truth from lies, true good fortune from evil fortune, and, thus, seeing he does not see and acts by touching like the blind.
Does he live in good fortune? He becomes violent, as an untrained and unrestrained horse, and does not see that with this good fortune God draws him to Himself as a father of a little child draws an apple. Will misfortune visit him? He grumbles, is indignant and blames, that as if he told a lie; he makes complaints and says a malicious word: "Am I a liar? In what have I sinned? Am I really more sinful than others? Am I worthy of this? Does my work deserve this?" He justifies himself, being full of every kind of untruth; he cleanses himself, being all besmirched; he considers himself unworthy of temporal punishment, but worthy of the eternal; he praises his merits, which stand for nothing.
