We find in Helaman 6:8-9 that by means of free trade, or "free intercourse one with another, to buy and to sell, and to get gain," both the Lamanites and Nephites "became exceedingly rich." According to Daniel Peterson, the principle underlying this situation is put in modern terms by the Nobel laureate economist Paul A. Samuelson, in his famous textbook Economics, 8th ed. (New York: McGraw-Hill, 1970), p. 668: "There is essentially only one argument for free or freer trade, but it is an exceedingly powerful one, namely: Unhampered trade promotes a mutually profitable international division of labor, greatly enhances the potential real national product of all countries, and makes possible higher standards of living all over the globe." (Emphasis in the original.) That the Book of Mormon so well depicts the operation of an economic law that was not generally recognized in Joseph Smith's time--and perhaps is not yet, even today--is a good illustration of its plausibility as authentic historiographical material. [Daniel C. Peterson, "Their Own Worst Enemies," in Studies in Scripture: Book of Mormon, Part 2, p. 106]