Why is the cross the most apt of Christian symbols? G.K. Chesterton offered a typically, well, Chestertonian answer in his masterpiece, Orthodoxy.

A circle, Chesterton wrote, suggests infinity and perfection, but a perfection "fixed forever in its size." By contrast, the cross "has at its heart a collision and a contradiction." And because of that, it "can extend its four arms forever without altering its shape. Because it has a paradox in its center it can grow without changing. The circle returns in upon itself and is bound. The cross opens its arms to the four winds; it is a signpost for free travelers."

Chesterton's insight into the universal embrace of the cross has a long pedigree in Christian theology; the Latin and Greek Fathers of the Church spoke of the cross in analogous ways. Thus that late first century manual of Christian prayers and practices, the Didache, describes the cross as a "sign of expansion." St. Cyril of Jerusalem picked up on that image, noting that only God could be so expansive: "On the cross," Cyril wrote, the Son of God "stretched out his hands to encompass the bounds of the universe." Lactantius, a Christian apologist of the late third and early fourth centuries, saw in the cross a foreshadowing of the universal Church: in Christ's suffering, "God stretched out his arms and embraced the world, thus prefiguring the coming of a people that would, from East and West, gather under his wings."

St. Athanasius, one of the greatest of the Greek Fathers, pondered the cross of Christ surrounded by two other crosses, and saw in that scene on Calvary the reconciliation of Jew and Gentile into the one People of God: Christ, God made man, and thus made a creature capable of standing erect and extending his hands, reaches out to the two thieves, who figuratively represent the two peoples to be gathered into the one Church. And in his reaching out, the God-man tears down the walls of division between Jew and Gentile and extends God's covenant of faithful love to the whole of believing humanity. The cross, by pointing in all four directions, symbolizes the radical inclusivity of God's redeeming purposes.

And thus Hans Urs von Balthasar, the 20th century Swiss theologian from whom I've borrowed these patristic images, suggests that the cross of Christ is the ultimate ground of solidarity: solidarity among the members of the human race; solidarity between humanity and God.

Chesterton saw a "collision and a contradiction" at the heart of the cross. Balthasar takes a different tack and sees, at the center of the cross, not so much colliding wood but the sacred heart of Jesus. The heart of Christ crucified is, Balthasar writes, the fountain of the Church: "It is at the moment when Jesus suffers the most absolute thirst that he dissolves, to become an eternal fountain." And from that fountain pour forth water and blood, Baptism and the Holy Eucharist: the sacrament from which the Church is born, and the sacrament from which the Church lives. In handing over his sacred heart in a perfect act of obedience to the will of the Father, Jesus redeems our wayward hearts, and makes it possible for us to make a gift of ourselves --- to hand over to others, in love, that which is most intimate and personal to us.

Three times in my life, I have had the privilege of praying at the twelfth station of the cross --- Calvary --- in the Church of the Holy Sepulcher in Jerusalem. The memories of jostling one's way through the Old City's narrow, winding streets, the noise of the tourists, and the cacophony of contending rites and sects in the basilica all fade away. It is, perhaps, the easiest place to pray in the world --- and not so much prayer in the sense of formulated words, but prayer as "practicing the presence." At the twelfth station, we are immersed in the sacred heart of Christ.

And there we find the center of the world, and the truth of the world's story. That is why it's "Good" Friday.

George Weigel is a senior fellow of the Ethics and Public Policy Center in Washington, D.C.