We are summoned to improve that gift--to "_let_ the peace of Christ" have its way in our hearts. The surest way to increase our possession of it is to decrease our separation from Him. The fulness of our possession of His gift of peace depends altogether on our proximity to the Giver. It evaporates in carrying. It "diminishes as the square of the distance" from the source. So the exhortation to let it rule in us will be best fulfilled by keeping thought and affection in close union with our Lord.
This peace is to "rule" in our hearts. The figure contained in the word here translated _rule_ is that of the umpire or arbitrator at the games, who, looking down on the arena, watches that the combatants strive lawfully, and adjudges the prize. Possibly the force of the figure may have been washed out of the word by use, and the "rule" of our rendering may be all that it means. But there seems no reason against keeping the full force of the expression, which adds picturesqueness and point to the precept. The peace of Christ, then, is to sit enthroned as umpire in the heart; or, if we might give a mediaeval instead of a classical shape to the figure, that fair sovereign, Peace, is to be Queen of the Tournament, and her "eyes rain influence and adjudge the prize." When contending impulses and reasons distract and seem to pull us in opposite directions, let her settle which is to prevail. How can the peace of Christ do that for us? We may make a rude test of good and evil by their effects on our inward repose. Whatever mars our tranquillity, ruffling the surface so that Christ's image is no longer visible, is to be avoided. That stillness of spirit is very sensitive and shrinks away at the presence of an evil thing. Let it be for us what the barometer is to a sailor, and if it sinks, let us be sure a storm is at hand. If we find that a given course of action tends to break our peace, we may be certain that there is poison in the draught which as in the old stories, has been detected by the shivered cup, and we should not drink any more. There is nothing so precious that it is worth while to lose the peace of Christ for the sake of it. Whenever we find it in peril, we must retrace our steps.
Then follows appended a reason for cultivating the peace of Christ "to which also ye were called in one body." The very purpose of God's merciful summons and invitation to them in the gospel was that they might share in this peace. There are many ways of putting God's design in His call by the gospel--it may be represented under many angles and from many points of view, and is glorious from all and each. No one word can state all the fulness to which we are called by His wonderful love, but none can be tenderer and more blessed than this thought, that God's great voice has summoned us to a share in Christ's peace. Being so called, all who share in it of course find themselves knit to each other by possession of a common gift. What a contradiction then, to be summoned in order to so blessed a possession, and not to allow it sovereign sway in moulding heart and life! What a contradiction, further, to have been gathered into one body by the common possession of the peace of Christ, and yet not to allow it to bind all the members in its sweet fetters with cords of love! The sway of the "peace of Christ" in our hearts will ensure the perfect exercise of all the other graces of which we have been hearing, and therefore this precept fitly closes the series of exhortations to brotherly affections, and seals all with the thought of the "one body" of which all these "new men" are members.