Watchfulness is the spiritual vigilance the believer is commanded to maintain—a wakeful, alert guarding of his own heart and life against sin and temptation, a sober readiness against the assaults of the world, the flesh, and the devil, and an expectant looking for the coming of his Lord. The Lord pressed it upon His disciples in Gethsemane: ‘Watch and pray, that ye enter not into temptation: the spirit indeed is willing, but the flesh is weak.’ It runs throughout the apostolic exhortations: ‘Watch ye, stand fast in the faith’; ‘Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour’; ‘let us watch and be sober.’ Watchfulness has several objects. There is the watching over the heart—‘keep thy heart with all diligence; for out of it are the issues of life’—the constant guard upon one’s thoughts, affections, and motives, where sin first conceives. There is the watching against temptation—the alert avoidance of occasions of sin and the readiness to resist the tempter’s approaches before they gain a foothold. There is the watching against the enemy—the sober awareness that a real adversary prowls, seeking the believer’s ruin, who must be resisted steadfast in the faith. And there is the watching for Christ’s coming—the expectant readiness of the servant who looks for his Lord, that whenever He comes He may find him watching, lest that day come upon him unawares. Watchfulness is the opposite of the spiritual sleep, drowsiness, and presumption that lull the soul into carelessness, where temptation finds it unguarded and the enemy finds it off its watch. It is closely joined to prayer (‘watch and pray’) and to sobriety, and it is the constant posture of the wise and faithful Christian, who knows that he wars in enemy territory, that his own heart is treacherous, and that his Lord may come at any hour. To be watchful is to be awake, alert, and ready; to be unwatchful is to invite the very ruin a moment’s vigilance would have prevented.