the Experimentum crucis, or that Experiment, which points out the Way we should follow, in any Doubt or Ambiguity. We have found Instances, wherein private Interest was separate from public; wherein it was even contrary: And yet we observ'd the moral Sentiment to continue, notwithstanding this Disjunction of Interests. And wherever these distinct Interests sensibly concur'd, we always found a sensible Encrease of the Sentiment, and a more warm Affection to Virtue, and Detestation of Vice, or what we properly call, Gratitude and Revenge. Compell'd by these Instances, we must renounce the Theory, which accounts for every moral Sentiment by the Principle of Self-love. We must adopt a more public Affection, and allow, that the Interests of Society are not, even on their own Account, altogether indifferent to us. Usefulness is only a Tendency to a certain End; and 'tis a Contradiction in Terms, that any Thing pleases as Means to an End, where the End itself does no way affect us. If therefore Usefulness be a Source of moral Sentiment, and if this Usefulness be not always consider'd with a Reference to Self; it follows, that every Thing, which contributes to the Happiness of Society, recommends itself directly to our Approbation and Good-will. Here is a Principle, which accounts, in great Part, for the Origin of Morality: And what need we seekfor
