Fear is a universal emotion and is typically depicted as a despicable one. While fear is regarded as nature's imperfect wisdom, often undesirable, and a sign of weakness, its role in maintaining human life is overlooked. In the middle of ubiquitous repulsion against fear, there is minuscule literature on the beneficial effects of fear and the consequences of fearlessness. Recent research has thrown light into the unconscious processing of fear. In sharp contrast to the existing literature, this book argues that fear, overriding all other emotions, operates relentlessly in the unconscious mind as a motivating force and renders life compatible with survival. Fear appeals can bring healthy behavioral changes; the stronger the appeal, the more persuasive it is. Moderate anxiety can improve performance that involves dominant responses. Social anxiety is regarded as the root cause of conscientiousness. This hypothesis is supported by the latest research that reveals impaired fear processing in patients with psychopathy, a condition that is associated with crimes. This book expands the concept of eustress, a positive reaction to stress, and describes the beneficial aspects of fear. The book gives a twist to the conventional view of fear as an unwanted emotion and draws a new hypothesis that fear is the primary emotion and a constant psychological operative, a lack of which poses dangerous consequences.