Read it through once

The regulation of this influence is the object of moral science. We know that we are susceptible of receiving painful or pleasurable impressions of greater or less intensity and duration. That is called good which produces pleasure; that is called evil which produces pain. These are general names, applicable to every class of causes, from which an overbalance of pain or pleasure may result. But when a human being is the active instrument of generating or diffusing happiness, the principle through which it is most effectually instrumental to that purpose, is called virtue. And benevolence, or the desire to be the author of good, united with justice, or an apprehension of the manner in which that good is to be done, constitutes virtue.