6 But yet, seeing that for lusts' sake, or even wickednesses, seeing, in a word, that for this temporal life and good men do wonderfully bear the brunt of many horrible sufferings, they much admonish us how great things ought to be borne for the sake of a good life, that it may also hereafter be eternal life, and without any bound of time, without waste or loss of any advantage, in true felicity secure. The Lord says, “In your patience you shall possess your souls:” He says not, your farms, your praises, your luxuries; but, “your souls.” If then the soul endures so great sufferings that it may possess that whereby it may be lost, how great ought it to bear that it may not be lost? And then, to mention a thing not culpable, if it bear so great sufferings for saving of the flesh under the hands of chirurgeons cutting or burning the same, how great ought it to bear for saving of itself under the fury of any soever enemies? Seeing that leeches, that the body may not die, do by pains consult for the body's good; but enemies by threatening the body with pains and death, would urge us on to the slaying of soul and body in hell.
Source: On Patience (New Advent)