Melius est peccatum cauere quam emendare. Facilius enim resistimus hosti a quo nondum uicti sumus, quam ei a quo iam superati ac deuicti cognoscimur. Omne peccatum, antequam admittatur, amplius pertimescitur. Quamuis autem graue sit, dum in usum uenerit, leue existimatur, et sine ullo metu committitur. Istis fomitibus, quasi quibusdam gradibus, coalescit omne peccatum: cogitatio namque praua delectationem parit; delectatio consensionem, consensio actionem, actio consuetudinem, consuetude necessitatem. Sicque his uinculis homo inplicatus, quadam catena uitiorum tenetur adstrictus, ita ut ab ea euelli nequaquam ualeat, nisi diuina gratia manum iacentis adprehendat.
It is better to avoid sin than to correct it. For it is easier to resist an enemy by whom we have never been defeated, than one who has once seen us overcome and conquered. Every sin is more feared before we have once allowed ourselves to give in to it. However great the sin, as soon as has come to be carried out in action, it is considered light, and committed without any fear. From such kindling wood, as from the rungs of a ladder, all sin is built up: perverse thoughts give rise to pleasure, pleasure to consent, consent to action, action to habit, habit to necessity. The man who is caught in such bonds is as it were chained and held fast by vice; he can never escape unless the Grace of God take his hand as he lies on the ground. (St Isidore of Seville, Sententiae II, 23 1-3; cf. Smaragdus of Saint-Mihiel, Diadema Monachorum, 34).