Monetary instruments are securities. As such, they have a term to maturity (instantaneous) and an issuer—often a central bank or private banks—that promises to pay the bearer the full face value. Gold coins are a collateralized form of such security. Paper, cheap metal, and electronic entries are the forms such securities take today. The characteristics of these securities allow them to circulate at a stable nominal value (par) in the right financial infrastructure and as long as the creditworthiness of the issuer is strong. This provides a reliable means to complete transactions and, more important, service debts.
Source: As a Currency, Bitcoin Violates All the Rules of Finance
wonkmonk's notes 