This work analyzes two texts by Daniel Defoe that were published shortly after the Great Plague of Marseille. In both Due Preparations and A Journal of the Plague Year, the narrators explore the ideas of a failing economy and a loss of faith. They link the plague to moral decay in society, describing it as both a biological occurrence related to the risks of international trade and a divine punishment. The plague itself is presented as a form of circulation connected firstly to the concept of credit as an invisible corruption of trade and secondly to the spread of atheism among the population. In this study, I argue that Defoe chose to write about the plague not only because it was a popular topic at the time but also because he was concerned with the idea of moral decay affecting both the body politic and the souls of the people.