“In the first place, purity is an “ability” or, in the traditional language of anthropology and ethics, an attitude. And in this sense it is a virtue. When this ability, that is, virtue, leads to abstaining ‘from unchastity,’ it does so because the man who possesses it knows ‘how to keep his own body with holiness and reverence, not as the object of lustful passions.'”
Source: Pope St. John Paul II, Man and Woman He Created Them, Pauline Books and Media, 2006.