Abstract: The understanding of money has always puzzled thinkers of all ages. From the history of economic thought development, there are two ways of thinking: the mainstream way of thinking about money as a commodity and the non-mainstream way of thinking about money as credit. The mainstream understanding way regards currency as a commodity, with the transaction media function as the foundation to derive the value storage and value scale functions. Thus two analytical frameworks are formed based on the transaction media and value storage, but they have encountered fundamental problems that are difficult to solve. The non-mainstream understanding ideas have a similarly long history, but they also have insurmountable theoretical limitations in terms of argumentation foundation, theoretical construction, and policy recommendations. In view of the theoretical difficulties existing in both ideas, they can be integrated from the perspective of Marx’s duality so as to dialectically understand the multiple connotations of money and lay a realistic foundation for the development of monetary theory.

Key words: currency; understanding ideas; commodity theory; credit theory; history and evaluation