A man, brought to the brink of a precipice, cannot look down without trembling; and the sentiment of imaginary danger actuates him, in opposition to the opinion and belief of real safety.  But the imagination is here assisted by the presence of a striking object; and yet prevails not, except it be also aided by novelty, and the unusual appearance of the object.  Custom soon reconciles us to heights and precipices, and wears off these false and delusive terrors.  The reverse is observable in the estimates which we form of characters and manners; and the more we habituate ourselves to an accurate scrutiny of morals, the more delicate feeling do we acquire of the most minute distinctions between vice and virtue.  Such frequent occasion, indeed, have we, in common life, to pronounce all kinds of moral determinations, that no object of this kind can be new or unusual to us; nor could any false views or prepossessions maintain their ground against an experience, so common and familiar.  Experience being chiefly what forms the associations of ideas, it is impossible that any association could establish and support itself, in direct opposition to that principle.

Usefulness is agreeable, and engages our approbation.  This is a matter of fact, confirmed by daily observation.  But, useful?  For what?  For somebody’s interest, surely.  Whose interest then?  Not our own only:  For our approbation frequently extends farther.  It must, therefore, be the interest of those, who are served by the character or action approved of; and these we may conclude, however remote, are not totally indifferent to us.  By opening up this principle, we shall discover one great source of moral distinctions.

PART II.

Self-love is a principle in human nature of such extensive energy, and the interest of each individual is, in general, so closely connected with that of the community, that those philosophers were excusable, who fancied that all our concern for the public might be resolved into a concern for our own happiness and preservation.  They saw every moment, instances of approbation or blame, satisfaction or displeasure towards characters and actions; they denominated the objects of these sentiments, virtues, or vices; they observed, that the former had a tendency to increase the happiness, and the latter the misery of mankind; they asked, whether it were possible that we could have any general concern for society, or any disinterested resentment of the welfare or injury of others; they found it simpler to consider all these sentiments as modifications of self-love; and they discovered a pretence, at least, for this unity of principle, in that close union of interest, which is so observable between the public and each individual.