He sensed at a primal, almost olfactory level that the game could only be as successful as the stability of its virtual currency. This led him to investigate the history of money and particularly of gold. Gold, he learned, was considered to be a reliable store of value because extracting it from the ground required a certain amount of effort that tended to remain stable over time. When new, easy-to-mine gold deposits were found, or new mining technologies developed, the value of gold tended to fall.