Mr Cannan, in his edition of the Wealth of Nations, very judiciously points out in a note on this passage that ’it is by no means clear what object there could be in exchanging one bone for another’.  Probably if one rummaged the literature of dog stories one would find plenty of examples of commerce between dogs, and when they perform tricks to get food, we detect the germ of the exchange of a service for a commodity.

When a bee takes honey from a flower and leaves in exchange the pollen from a flower of an opposite sex, it may be said to be at once a merchant, a carrier, and a matrimonial agent, and the brilliant colours with which flowers attract these merchants have been compared to the advertising posters of the human trader.  But however the case may be in the animal and vegetable world, there can be no question that the trading instinct appears at a very early stage of human development.  In boys the instinct to trade or swop articles appears long before they feel any inclination to fall in love or to give much serious thought to religion.  The classical example is given by Mark Twain, who relates how Tom Sawyer exchanged one of his own teeth, which had been pulled out that morning, for a tick in the possession of Huckleberry Finn, and then ‘the two boys separated, each feeling wealthier than before’.  In fact, of course, they both were wealthier than before, because each had got something that he wanted more than the article with which he had parted; and this pleasant result sums up the whole genesis and basis of commerce.

But though commerce is thus merely an expression of an instinct which is primitive and universal, it does not follow that it is its only or even its earliest expression.  Perhaps its earliest and most natural expression was through robbery, with or without violence.  A primitive savage who saw something that he wanted would probably, if strong enough, hit its owner on the head and take it, and this short and simple method of acquisition still occasionally reappears in the realms of the most highly civilized diplomacy.  Nevertheless, at a very early stage its limitations became obvious, and quite at the dawn of recorded history we find commercial transactions referred to as an established branch of human intercourse.  The Old Testament story has not gone far before it tells us of buying and selling.  In the twenty-third chapter of Genesis we find a very interesting bargain recorded between Abraham and Ephron.  Sarah had died in Kirjath-arba: 

’the same is Hebron in the land of Canaan:  and Abraham came to mourn for Sarah, and to weep for her.  And Abraham stood up from before his dead, and spake unto the sons of Heth, saying, I am a stranger and a sojourner with you:  give me a possession of a buryingplace with you, that I may bury my dead out of my sight.  And the children of Heth answered Abraham, saying unto him, Hear us, my lord:  thou art a mighty prince among us:  in the choice of our sepulchres