Thus we seem, upon the whole, to have attained a knowledge of the force of that principle here insisted on, and can determine what degree of esteem or moral approbation may result from reflections on public interest and utility.  The necessity of justice to the support of society is the sole foundation of that virtue; and since no moral excellence is more highly esteemed, we may conclude that this circumstance of usefulness has, in general, the strongest energy, and most entire command over our sentiments.  It must, therefore, be the source of a considerable part of the merit ascribed to humanity, benevolence, friendship, public spirit, and other social virtues of that stamp; as it is the sole source of the moral approbation paid to fidelity, justice, veracity, integrity, and those other estimable and useful qualities and principles.  It is entirely agreeable to the rules of philosophy, and even of common reason; where any principle has been found to have a great force and energy in one instance, to ascribe to it a like energy in all similar instances.  This indeed is Newton’s chief rule of philosophizing [Footnote:  Principia.  Lib. iii.].

SECTION IV.

Of political society.

Had every man sufficient sagacity to perceive, at all times, the strong interest which binds him to the observance of justice and equity, and strength of mind sufficient to persevere in a steady adherence to a general and a distant interest, in opposition to the allurements of present pleasure and advantage; there had never, in that case, been any such thing as government or political society, but each man, following his natural liberty, had lived in entire peace and harmony with all others.  What need of positive law where natural justice is, of itself, a sufficient restraint?  Why create magistrates, where there never arises any disorder or iniquity?  Why abridge our native freedom, when, in every instance, the utmost exertion of it is found innocent and beneficial?  It is evident, that, if government were totally useless, it never could have place, and that the sole foundation of the duty of allegiance is the advantage, which it procures to society, by preserving peace and order among mankind.

When a number of political societies are erected, and maintain a great intercourse together, a new set of rules are immediately discovered to be useful in that particular situation; and accordingly take place under the title of Laws of Nations.  Of this kind are, the sacredness of the person of ambassadors, abstaining from poisoned arms, quarter in war, with others of that kind, which are plainly calculated for the advantage of states and kingdoms in their intercourse with each other.