44. What of justice that pertains to God? As the Lord says, "Ye cannot serve two masters," 117 and the apostle denounces those who serve the creature rather than the Creator, 118 was it not said before in the Old Testament, "Thou shalt worship the Lord thy God, and Him only shalt thou serve?" 119 I need say no more on this, for these books are full of such passages. The lover, then, whom we are describing, will get from justice this rule of life, that he must with perfect readiness serve the God whom he loves, the highest good, the highest wisdom, the highest peace; 120 and as regards all other things, must either rule them as subject to himself, or treat them with a view to their subjection. This rule of life, is, as we have shown, confirmed by the authority of both Testaments.
45. With equal brevity we must treat of prudence, to which it belongs to discern between what is to be desired and what to be shunned. Without this, nothing can be done of what we have already spoken of. It is the part of prudence to keep watch with most anxious vigilance, lest any evil influence should stealthily creep in upon us. Thus the Lord often exclaims, "Watch;" 121 and He says, "Walk while ye have the light, lest darkness come upon you." 122 And then it is said, "Know ye not that a little leaven leaveneth the whole lump?" 123 And no passage can be quoted from the Old Testament more expressly condemning this mental somnolence, which makes us insensible to destruction advancing on us step by step, than those words of the prophet, "He who despiseth small things shall fall by degrees." 124 On this topic I might discourse at length did our haste allow of it. And did our present task demand it, we might perhaps prove the depth of these mysteries, by making a mock of which profane men in their perfect ignorance fall, not certainly by degrees, but with a headlong overthrow.