In the Bible, there is an intriguing allegorical account that man's fall from his paradisal state was caused by man eating the forbidden fruit from the Tree of the Knowledge of Good and Evil. Man's eyes were "opened" to know the distinction between good and evil (Genesis 3). In other words, when man becomes intellectually developed to distinguish between good and bad, he realizes that is a gap between what he considers good or ideal and what he is experiencing. The perception of this disparity is what creates psychological and physiological tension.