The implications of controlling one’s thoughts are huge. One arena of life in which much damage is caused by the secular position is that there are no bad thoughts in married life. Mainstream magazines often quote therapists who encourage sexual fantasizing as harmless and at times even beneficial. The truth is that male human nature being what it is, no real live woman, let alone a wife who has borne him a child or two, can possibly match up to the object of her husband’s fantasies. Likewise, few middle-aged men would win the Mr. Olympia contest. Why would anyone encourage husbands or wives to engage in behavior that can only make them less content in their marriage?
Children raised with no ability or desire to restrain their fantasies of sensual and material appetites are being condemned to a life of constant dissatisfaction. Dissatisfaction regularly leads to resentment and then envy. It is a short step from envy to a justification for taking what is not rightfully yours, or to exacerbating your problems by blaming them on anyone but yourself.
Rabbi Daniel Lapin, "America's Real War," pg.253-254