Keynes' project for an International Clearing Union does not respond only to the economic and political needs of the particular historical moment in which it was conceived, i.e. the establishment of an international money really complementary to national currencies. With that project, in fact, Keynes conceives a new kind money, whose positive character is to be un-hoardable. The non-hoardability of the bancor raises the issue of the nature of what is commonly known as 'liquidity', and allows not only to distinguish the liquidity that is proper to money from liquidity in general, but also to refine the concept of liquidity in itself. And finally, it allows to think about the very possibility of other forms of monetary complementarity, notabl...