1. Most people place prudence and wisdom in the searching out and discovery of truth. I believe this is because neither can one rightly be called wise who lacks prudence, nor prudent who lacks wisdom. Wherefore, if the office of prudence and wisdom is taken to be nothing else than the inquiry into and comprehension of truth, then he who has been able to seek truth prudently and to discover it wisely will rightly be called prudent and wise. This I have set down beforehand, so that whatever shall have been argued concerning prudence may be understood to be said entirely also of wisdom. For these two virtues are so interwoven and united with one another, and either of them so cannot be without the other, that neither can wisdom be called imprudent, nor prudence be called unwise.
If therefore the whole perfection of human life consists in action and in knowledge: just as we have proved that the action of temperance and of fortitude is fulfilled by the consummation of justice, so let us establish that the knowledge of things comes about by the attainment of prudence. 1. The knowledge of things which proceeds from the fountain of prudence and wisdom illuminates all the spiritual, who are cleansed from carnal vices; and, turning them away from every delight of harmful curiosity, it inflames them with the desire of contemplating virtue: so that, having attained the knowledge of things human and divine, they may truly become prudent and wise, may foresee the impending evils and at the same time guard against them, and may not think anything to be evils except those which make men evil;
nor may any perturbations, as it were to those ignorant of them, shake out anything of their modesty or tranquility; let them distinguish between deceptive and solid goods; let them prudently accept that nothing in this world happens by chance or unjustly, but that all things come to pass, God willing and permitting them; let them either wisely teach those who understand otherwise, or refute them; let them understand that the various pains and diverse infirmities which afflict those living mortally do not always follow upon preceding sins, but for the most part befall those born corruptibly from the very condition of mortality; and, knowing that they are not condemned by present adversities but proved, let them, acting manfully, seize from the very endurance of sufferings an occasion of acquiring patience for themselves;
and let them neither harm others, nor permit themselves to be harmed. 5. The Lord commanded that such men be made in the Gospel, saying: Be ye prudent as serpents, and simple as doves (Matt. x. 16): because the simple can deceive no one, nor do the prudent permit themselves to be deceived. But if, in any contract whatever, or in conversation, or in any other matter whatsoever, anyone does not allow himself to be deceived, and yet himself deceives another, that man does not have prudence—which is the cause of salvation rather than of destruction—but counterfeits it. For virtue differs from vice in this, that vice corrupts what is sound, whereas virtue heals what has been corrupted by the access of vice:
and thus the truly prudent man hastens to be of profit to all whom he can, truthfully, so that by his merits the fruit may increase of all who are gained for God through him; or, if he plots the destruction of anyone, or exults over the fall of one perishing, it is necessary that he himself perish first before he destroys another, and that from himself that destruction begin by which he desires another to perish.