As the translations of the New Roman Missal help Catholics see the Eucharistic Liturgy with new eyes, and as they gather in Dublin for the 50th International Eucharistic Congress, Brendan Leahy offers this loving explanation of the dual dimension of the Mass – Christ's gift and our existential participation, His action and our daily cooperation. By reflecting on the parts of the Mass, Leahy draws out the meaning and value of what happens at Mass, and what we say and do in response – from our mental and spiritual state as we enter the church, through the opening procession, to the final blessing and out into the relationships that make up our daily life. Rich descriptions of the theology behind the elements of the Mass are enfleshed by concrete stories of how real people contribute to what Jesus Christ, through the power of the Holy Spirit, wants his great gift of the Eucharist to achieve: shaping families and peoples, tribes and nations, cities, and the cosmos according to the great dream that He shared the night before He died when he prayed to the Father: "that they may all be one" (Jn 17:21).