I argue for the existence of a ‘ratcheting-up effect’: the behavior of moral saints serves to increase the level of moral obligation the rest of us face. What we are morally obligated to do is constrained by what it would be reasonable for us to believe we are morally obligated to do. Moral saints provide us with a special kind of evidence that bears on what we can reasonably believe about our obligations. They do this by modeling the level of sacrifice a person can realistically bear. Exposure to moral saints thus ‘ratchets-up’ our obligations by combating a type of ignorance that would otherwise defeat those obligations.