Land and Labour, so as we might express the value by either of them alone as well or better then by both, and reduce one into the other as easily and certainly as we reduce pence into pounds. Wherefore we would be glad to finde the natural values of the Fee simple of Land, though but no better then we have done that of the usus fructus above-mentioned, which we attempt as followeth.
19. Having found the Rent or value of the usus fructus per annum, the question is, how many years purchase (as we usually say) is the Fee simple naturally worth? If we say an infinite number, then an Acre of Land would be equal in value to a thousand Acres of the same Land; which is absurd, an infinity of unites being equal to an infinity of thousands. Wherefore we must pitch upon some limited number, and that I ap-|27|prehend to be the number of years, which I conceive one man of fifty years old, another of twenty eight, and another of seven years old, all being alive together may be thought to live[1]; that is to say, of a Grandfather, Father, and Childe; few men having reason to take care of more remote Posterity: for if a man be a great Grandfather, he himself is so much the nearer his end, so as there are but three in a continual line of descent usually co-existing together; and as some are Grandfathers at forty years, yet as many are not till above sixty, and sic de cæteris.
20. Wherefore I pitch the number of years purchase, that any Land is naturally worth, to be the ordinary extent of three such persons their lives. Now in England we esteem three lives equal to one and twenty years, and consequently the value of Land, to be about the same number of years purchase. Possibly if they thought themselves mistaken in the one, (as the observator on the Bills of Mortality thinks they are[2]) they would alter in the other, unless the consideration of the force of popular errour and dependance of things already concatenated, did hinder them.
21. This I esteem to be the number of years purchase where Titles are good, and where there is a moral certainty of
