That good thing that was committed to you to keep—how?—by the Holy Spirit, who dwells in us. For it is not in the power of a human soul, when instructed with things so great, to be sufficient for keeping them [of himself]. And why? Because there are many robbers and thick darkness, and the devil is still at hand to plot against us; and we know not what is the hour, what the occasion for him to set on us. How then, he means, shall we be sufficient for keeping them? By the Holy Spirit—that is if we have the Spirit with us, if we do not expel grace, he will stand by us. For, Except the Lord build the house, they labor in vain who build it. Except the Lord keep the city, the watchman wakes but in vain. This is our wall, this our castle, this our refuge. If therefore he dwells in us and is himself our guard, what need is there for the commandment? That we may hold him fast, may keep him and not banish him by our evil deeds.

But someone, perhaps, will say, I did indeed receive faith, but it is I who have guarded and kept it. You perhaps say this, whoever you are, listening to all this and having no sense: I received faith, but it is I who have guarded and kept it. It is not what our Paul says, It is I who have guarded and kept it. He had his eyes, you see, on [the words] unless the Lord keeps watch over the city, he labors in vain who guards it. Labor, by all means, guard it; but it is good for you that you are being guarded. Because you are not up to guarding yourself. If you are left to yourself, you will doze off and fall asleep. He, though, does not doze nor sleep, the one who guards Israel.^[1]

He claims that this is how an Epicurus^[1] would speak, or an Aristippus^[2] and his Cyrenian flowers,^[3] or the other philosophers who preach carnal pleasures. But when I diligently reconsider the question, I find nothing to support such vile conclusions that everything happens by chance and that fortune has free rein in human affairs. Rather the truth is that everything is under God’s judgment. The fleet of foot ought not to think that the footrace is his, any more than the strong person should confide in his brute strength. Nor should the wise person reckon that wealth and opulence go with prudence, nor should the learned orator reckon that he can find favor with the crowd because of his learning and eloquence. Rather, everything happens by the disposition of God, and except he govern everything by his will and build the house, they labor in vain who build it. And unless he guard the city, they keep watch in vain who set a guard over it.

Atticus:^[1] Therefore, they are wrong in their thinking who rule out the help of God in every single action that we perform and who seek to twist the true meaning to other meanings by putting forth interpretations that are perverted, nay more, worthy of ridicule, on the following passage: Except the Lord build the house, they labor in vain that build it. Except the Lord keep the city, he watches in vain who keeps it.

The cowl^[1] is a symbol of the charity of God our Savior. It protects the most important part of the body and keeps us, who are children in Christ, warm. Thus it can be said to afford protection against those who attempt to strike and wound us. Consequently, all who wear this cowl on their heads sing these words aloud: If the Lord does not build the house and keep the city, in vain does the builder labor and the watchman stand his guard. Such words as these instill humility and root out that long-standing evil, which is pride and which caused Lucifer, who rose like the day star in the morning, to be cast down to the earth.