Tractatus de contractibus shows that there are mainly three fundamental economic views that characterize the originality and the acuteness of Olivi’s thought: a subject-based theory of value, a theory of just price, and the theoretical-systematic use of the concept of capital. Olivi’s distinction between simply sterile money and fertile, lucrative money – called capitale (capital) – is central. His – at that time – revolutionary thought challenges the theory of money as a mere means of exchange; he acknowledged the legitimacy of trade and the added value (valor superadiunctus) of capital. Thus, he allowed a price as compensation or as remuneration for the owner’s foregone use of the capital. This is not a mere scholastic subtlety, but it is a serious attempt to grasp different phenomena with different concepts.