Economic growth and higher level of resources have been shown to have important effects on human preferences: when resources are abundant, individuals tend to be more future-oriented and to be able to defer immediate gratifications in order to get delayed but higher rewards. In this paper, we build on these evidences to explain the rise of self-discipline and asceticism during the Medieval period. We demonstrate that the increasing prosperity enjoyed by Europeans shifted their preferences away from impulsive and present-oriented behaviors toward future-oriented behaviors. To do so, we construct a unique database of saints to measure the historical importance of ascetic values. We use soil suitability to the introduction of the heavy plow as an instrument for economic prosperity, as measured by population density and urbanization, to identify the causal impact of economic prosperity on ascetic values. Our results show that a rise in economic prosperity led to a rise in the proportion of saints described as ascetic. We argue that this effect reflects an endogenous change in local preferences away from purely materialistic motivations toward self-discipline, and the renunciation of immediate pleasures for longer-term and spiritual goals. This paper provides first longitudinal and causal evidence that economic development can have a causal effect on individual preferences and religious values in history.