I think she's referring to the bigger picture - the use of money as a token of value represents an act of faith. On pound notes this act of faith is embodied in the statement "I promise to pay the bearer on demand the sum of ~", which underscores the fact that what is being accepted as legal tender is a representation of value, having no intrinsic worth. And what happens when this faith starts to crumble? Ask rural bankers in the goldrush era, ask starving women in the Weimar republic...