The times on sin continues with this on sloth-

To the medieval theologians, however, sloth was more than simply lazing around. It was the self-indulgent desire for ease, ignoring God�s known will. Thomas Aquinas defined sloth as �sluggishness of the mind which neglects to being good�, and said it drew man away from good deeds. A slothful person, the moralists concluded, was not only morally deficient, but knowingly perpetrated evil by failing to make the effort to do good.