Wherein I totally rip-off another writer. Today's choice is Blessed John Paul the Great, and his apostolic letter, "Salvific Suffering":
In the Paschal Mystery Christ began the union with man in the community
of the Church. The mystery of the Church is expressed in this: that
already in the act of Baptism, which brings about a configuration with Christ,
and then through his Sacrifice—sacramentally through the Eucharist—the
Church is continually being built up spiritually as the Body of Christ. In this
Body, Christ wishes to be united with every individual, and in a special way
he is united with those who suffer. The words quoted above from the Letter to
the Colossians bear witness to the exceptional nature of this union. For, whoever
suffers in union with Christ— just as the Apostle Paul bears his "tribulations"
in union with Christ— not only receives from Christ that strength already
referred to but also "completes" by his suffering "what is
lacking in Christ's afflictions". This evangelical outlook especially
highlights the truth concerning the creative character of suffering. The
sufferings of Christ created the good of the world's redemption. This good in
itself is inexhaustible and infinite. No man can add anything to it. But at the
same time, in the mystery of the Church as his Body, Christ has in a sense
opened his own redemptive suffering to all human suffering. In so far as man
becomes a sharer in Christ's sufferings—in any part of the world and at
any time in history—to that extent he in his own way completes the
suffering through which Christ accomplished the Redemption of the world.
Does this mean that the Redemption achieved by Christ is not complete? No.
It only means that the Redemption, accomplished through satisfactory
love, remains always open to all love expressed in human suffering.
In this dimension—the dimension of love—the Redemption which has
already been completely accomplished is, in a certain sense, constantly being
accomplished. Christ achieved the Redemption completely and to the very limits
but at the same time he did not bring it to a close. In this redemptive
suffering, through which the Redemption of the world was accomplished, Christ
opened himself from the beginning to every human suffering and constantly does
so. Yes, it seems to be part of the very essence of Christ's redemptive
suffering that this suffering requires to be unceasingly completed.