In 1817 English economist David Ricardo published The Principles of Political Economy and Taxation in which he expounded the theory of comparative advantage, "a fundamental argument in favor of free trade among countries and of specialization among individuals. Ricardo argued that there is mutual benefit from trade (or exchange) even if one party (e.g. resource-rich country, highly-skilled artisan) is more productive in every possible area than its trading counterpart (e.g. resource-poor country, unskilled laborer), as long as each concentrates on the activities where it has relative productivity advantage" (Wikipedia article on David Ricardo, accessed 12-27-2008).
Concerning the economic value of rare books and manuscripts Ricardo included pertinent observations in Chapter One, Section 1, paragraph 4:
"There are some commodities, the value of which is determined by their scarcity alone. No labour can increase the quantity of such goods, and therefore their value cannot be lowered by an increased supply. Some rare statues, scarce books and coins, wines of a peculiar quality, which can only be made from grapes grown on a particular soil, of which there is very limited quanity, are all of this description. Their value is wholly independent of the quantity of labour necessary to produce them, and varies with the varying wealth and inclinations of those who desire to possess them."
Carter & Muir, Printing and the Mind of Man (1967) no. 277.