Once we understand the true purpose of money, we can identify the most ethical and desirable financial systems that serve this purpose. My book, The Philosophical Method, shows how money, at its core, is a tool to facilitate will. Not all our desires are mutually realisable. For instance, I cannot simultaneously holiday in both the US and Australia. I have only one body and this constrains what I can do at any one time. Furthermore, there are many tasks we cannot simultaneously perform for others. We cannot cook and drive a taxi at the same time, for example.