Roman Catechism 40.39

Chapter 40 — Part IV: Prayer — The Sixth Petition: Lead Us Not into Temptation

Section 39. The Author of victory over Temptation — But from the consideration of these victories achieved by holy men which we have mentioned, let no one indulge feelings of self-complacency, nor flatter himself that, by his own single unassisted exertions, he is able to withstand the temptations and hostile assaults of the demons. This is not within the power of human nature, nor within the capacity of human frailty.