Eccl 9:18

“"And wisdom is better than weapons, but a single rogue can ruin a great deal of good. "Now he also takes wisdom in preference to strength and says that it is worth more in battle than weapons. But if there is one fool, however small and worthless, he will repeatedly destroy riches and great wealth by his stupidity. But because the Hebrew can also be read as: 'and he who sins once, will lose much goodness', much righteousness will be lost in return and virtues will follow in turn, and he who has one, has all [Cfr. Cic de Offic. II, 35.]; and he who sins at one time, leaves himself open to all vices [Cfr. Iac. 2, 10.].”

“Likewise, the fruit of wisdom is born of the last four by contrast. Corresponding to this fruit, there are four acts, for wisdom is comforting, struggling, contemplating, and extolling. It comforts the good: "Wisdom is a better defense for the wise man than would be ten princes in the city." It is also struggling, against evil: "Better is wisdom than weapons of war." Again, Wisdom "gave him a strong conflict, that he might overcome and know that wisdom is mightier than all."”

“"Wisdom is better," etc. Here secondly he sets forth wisdom above the defense of armor, saying: "Wisdom is better than weapons of war," because weapons of war are for protection; likewise wisdom protects. Proverbs 2: "Counsel shall keep you, and prudence shall preserve you, that you may be delivered from the evil way and from the man who speaks perverse things." And that it protects better is clear, because he who loses wisdom through fault cannot defend himself by armor without losing many goods. Whence he says: "And he who shall sin in one thing," by departing from wisdom, according to what was said above in chapter 8: "Do not hasten to depart from his face, nor persist in an evil work." "Shall lose many good things"; for by sinning in one thing, he loses wisdom, and by losing it, he loses many good things. Wisdom 7: "All good things came to me together with her"; and therefore, when she is lost, many good things are lost. Or: "he who shall sin in one thing," against charity, "shall lose many good things," according to that saying in James 2: "He who sins in one thing is made guilty of all." And he makes this manifest through a metaphor, because the awareness of sin is compared to a dying fly, because it renders and produces abomination in the affection and in the conscience.”