QUOTE : As only that which works is real, so, according to St. Thomas, only good is real in the sense of “existing.” His argument, however, introduces a good that is tantamount to “convenient, sufficient, appropriate, suitable.” One ought therefore to translate “omne agens agit propter bonum” as: “Every agent works for the sake of what suits it.” That’s what the devil does too, as we all know. He too has an “appetite” and strives after perfection–not in good but in evil. Even so, one could hardly conclude from this that his striving is “essentially good.