The etymology of currency is from the 1650s, "condition of flowing," a sense now rare or obsolete, from Latin currens, present participle of currere "to run" (from PIE root *kers- "to run"). The notion of "state or fact of flowing from person to person" led to the senses "continuity in public knowledge" (1722) and "that which is current as a medium of exchange, money" (1729). The flow of currency is changing rapidly. Physical currency has morphed into virtual currency and now currency is morphing into tokens. Currency has been evolving over the centuries so it appears as if we are now in a new cycle of re-evaluating currency in our present culture.