What is Monetary base
The monetary base is defined as the total value of all currency (banknotes and coins) outside the central bank and commercial banks' (net) reserves with the central bank. The monetary base is a debt in the balance sheet of the central bank. Its assets are mostly comprised of the foreign exchange and gold reserves and bonds issued by the national government. Currency inside the central bank has no value - it is comparable to an "I owe you" written by yourself and held by yourself.