 Notwithstanding his brilliant argument for the neutrality of money, Hume recognized that the specie-flow mechanism was never fully achieved; trade barriers, transaction costs, and other interferences with the money supply limited its full operation. As a result, Hume endorsed the non-neutrality of money as more veridical. He argued that, from roughly 1500 to 1750, the money supply had increased by a factor of eight but the price level had only increased by a factor of four. The simple reason was significant economic growth, a doubling of output that required the extant money to service the significant increase in transactions. The growth was stimulated by many factors, the gains from trade, the division of labor, and the accumulation of capital. Hume also acknowledged the importance of new technologies and their rapid spread once in place. Above all, he discerned that money could engender growth, even though this remained mysterious and was not “easily accounted for” (Hume “Of Money” [1987: 288).