What did Jesus intend when he spoke the words, “This is my body”? The Lost Supper argues that Jesus’ words and actions at the Last Supper presupposed an already existing Passover ritual in which the messiah was represented by a piece of bread: Jesus was not instituting new symbolism but using an existing symbol to speak about himself. Drawing on both second temple and early Rabbinic sources, Matthew Colvin places Jesus’ words in the Upper Room within the context of historically attested Jewish thought about Passover. The result is a new perspective on the Eucharist: a credible first-century Jewish way of thinking about the Last Supper and Lord’s Supper— and a sacramentology that is also at work in the letters of the apostle Paul. Such a perspective gives us the historical standpoint to correct Christian assumptions, past and present, about how the Eucharist works and how we ought to celebrate it.