This paper approaches the shadow banking problem from a monetary point of view. It does so by means of a simple thought experiment. The aim is to strip away the inessentials so as to reveal some of the basic legal-institutional design considerations that attend the establishment and management of a monetary system. It is the author's experience that underlying assumptions in this area are surprisingly divergent and, at any rate, are seldom made explicit in the shadow banking literature. If this paper merely assists in surfacing some otherwise unstated assumptions, it will have served its purpose.