This work provides a detailed analysis of the development of Calvin's eucharistic doctrine. In doing so, it demonstrates the importance of examining the full range of Calvin's writings and dispels the notion that one need look only at the 1559 "Institutes" to grasp Calvin's eucharistic theology. Davis pinpoints the doctrine as the work of the Holy Spirit in the Eucharist, accommodation, instrumentality, and the Eucharist as a means of grace. There is a nuanced discussion of substantial partaking not duplicated elsewhere. Davis's work makes clear the exegetical foundations for much of Calvin's teaching on the Eucharist. Finally, Davis demonstrates that there are eucharistic gifts according to Calvin. The more general gift is that of true communion with the body and blood of Christ. However, the specific gift of the Eucharist is the assurance it brings believers of God's good will towards them. Thus, the text underscores Calvin's understanding of the Eucharist as an exhibition of the "clearest promises of God", namely, the promise of union with Christ and all which that entails.