39. The purport of this commandment is that since the Lord has bound the whole human race by a kind of unity, the safety of all ought to be considered as entrusted to each. In general, therefore, all violence and injustice, and every kind of harm from which our neighbour's body suffers, is prohibited. Accordingly, we are required faithfully to do what in us lies to defend the life of our neighbour; to promote whatever tends to his tranquillity, to be vigilant in warding off harm, and, when danger comes, to assist in removing it. Remembering that the Divine Lawgiver thus speaks, consider, moreover, that he requires you to apply the same rule in regulating your mind. It were ridiculous, that he, who sees the thoughts of the heart, and has special regard to them, should train the body only to rectitude. This commandment, therefore, prohibits the murder of the heart, and requires a sincere desire to preserve our brother's life. The hand, indeed, commits the murder, but the mind, under the influence of wrath and hatred, conceives it. How can you be angry with your brother, without passionately longing to do him harm? If you must not be angry with him, neither must you hate him, hatred being nothing but inveterate anger. However you may disguise the fact, or endeavour to escape from it by vain pretexts. Where either wrath or hatred is, there is an inclination to do mischief. If you still persist in tergiversation, the mouth of the Spirit has declared, that "whosoever hateth his brother is a murderer," (1 John 3:15); and the mouth of our Saviour has declared, that "whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, Raca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire," (Mt. 5:22).
40. Scripture notes a twofold equity on which this commandment is founded. Man is both the image of God and our flesh. Wherefore, if we would not violate the image of God, we must hold the person of man sacred--if we would not divest ourselves of humanity we must cherish our own flesh. The practical inference to be drawn from the redemption and gift of Christ will be elsewhere considered. The Lord has been pleased to direct our attention to these two natural considerations as inducements to watch over our neighbour's preservation--viz. to revere the divine image impressed upon him, and embrace our own flesh. To be clear of the crime of murder, it is not enough to refrain from shedding man's blood. If in act you perpetrate, if in endeavour you plot, if in wish and design you conceive what is adverse to another's safety, you have the guilt of murder. On the other hand, if you do not according to your means and opportunity study to defend his safety, by that inhumanity you violate the law. But if the safety of the body is so carefully provided for, we may hence infer how much care and exertion is due to the safety of the soul, which is of immeasurably higher value in the sight of God.