Central banks issue currency. (They issue reserves too, but "reserves" are just the name we give to central bank currency held by commercial banks in electronic form rather than in paper form, and it makes no difference whether money is printed on paper, on plastic, or on computer disks.) Commercial banks issue deposits. (They used to issue notes too, but again it makes no difference whether money is printed on paper, plastic, or on computer disks.)
Central bank currency is alpha; commercial bank deposits are beta. Commercial banks promise to convert their deposits into central bank currency at a fixed exchange rate; the central bank does not promise to convert its currency into commercial bank deposits at a fixed exchange rate. It is the commercial banks' responsibility to keep their exchange rates fixed. The alpha goes where he wants to go; and the betas follow the alpha. The central bank decides monetary policy.
In the olden days, under the gold standard, central banks promised to convert their currency into gold at a fixed exchange rate. Did this make gold the super-alpha?
I was reading David Glasner's good post on the 1920-21 recession. As expected, I learned some monetary history. But David has also caused me to re-think my views on the theory of the gold standard.