2 But in order to make my argument plainer, let us first of all enquire what injustice is, and of what kind of things the material of it is wont to be composed; also what human virtue is, and what it is which ruins it; and further what it is which seems to ruin it but really does not. For instance (for I must complete my argument by means of examples) each thing is subject to one evil which ruins it; iron to rust, wool to moth, flocks of sheep to wolves. The virtue of wine is injured when it ferments and turns sour: of honey when it loses its natural sweetness, and is reduced to a bitter juice. Ears of grain are ruined by mildew and drought, and the fruit, and leaves, and branches of vines by the mischievous host of locusts, other trees by the caterpillar, and irrational creatures by diseases of various kinds: and not to lengthen the list by going through all possible examples, our own flesh is subject to fevers, and palsies, and a crowd of other maladies. As then each one of these things is liable to that which ruins its virtue, let us now consider what it is which injures the human race, and what it is which ruins the virtue of a human being. Most men think that there are various things which have this effect; for I must mention the erroneous opinions on the subject, and, after confuting them, proceed to exhibit that which really does ruin our virtue: and to demonstrate clearly that no one could inflict this injury or bring this ruin upon us unless we betrayed ourselves. The multitude then having erroneous opinions imagine that there are many different things which ruin our virtue: some say it is poverty, others bodily disease, others loss of property, others calumny, others death and they are perpetually bewailing and lamenting these things: and while they are commiserating the sufferers and shedding tears they excitedly exclaim to one another “What a calamity has befallen such and such a man! He has been deprived of all his fortune at a blow.” Of another again one will say: “such and such a man has been attacked by severe sickness and is despaired of by the physicians in attendance.” Some bewail and lament the inmates of the prison, some those who have been expelled from their country and transported to the land of exile, others those who have been deprived of their freedom, others those who have been seized and made captives by enemies, others those who have been drowned, or burnt, or buried by the fall of a house, but no one mourns those who are living in wickedness: on the contrary, which is worse than all, they often congratulate them, a practice which is the cause of all manner of evils. Come then (only, as I exhorted you at the outset, do not make a commotion), let me prove that none of the things which have been mentioned injure the man who lives soberly, nor can ruin his virtue. For tell me if a man has lost his all either at the hands of calumniators or of robbers, or has been stripped of his goods by knavish servants, what harm has the loss done to the virtue of the man?
But if it seems well let me rather indicate in the first place what is the virtue of a man, beginning by dealing with the subject in the case of existences of another kind so as to make it more intelligible and plain to the majority of readers.
Source: No One Can Harm the Man Who Does Not Injure Himself (New Advent)