419. People who love what is good because it is good and love what is true because it is true have supreme love for their neighbor, because they love the Lord who is goodness itself and truth itself. Love for goodness, love for truth, and love for our neighbor come from nowhere else. Love for our neighbor, then, has a heavenly origin.

It is the same thing whether you say "goodness" or "usefulness. " Therefore doing good things is doing useful things. The amount and quality of usefulness that a given good thing has determines the amount and quality of its goodness.