  The nature of monetary arrangements is often discussed without any reference
to its detailed construction. We present a graph representation that allows for
a clear understanding of modern monetary systems. First, we show that systems
based on commodity money are incompatible with credit. We then study the
current chartalist systems based on pure fiat money, and we discuss the
consolidation of the central bank with the Treasury. We obtain a visual
explanation about how commercial banks are responsible for endogenous money
creation whereas the Treasury and the central bank are in charge of the total
amount of net money. Finally we draw an analogy between systems based on gold
convertibility and currency pegs to show that fixed exchange rates can never be
maintained.
