Saint Augustine, building upon such Pauline insights as "you are the body of Christ, and individually members of it ... If one member suffers, all suffer together, if one member is honored, all rejoice together" (1Cor 12:27,26), articulated his key insight into the "totus Christus," the whole Christ.
Strikingly, Augustine applied this insight to the Church's praying the psalms. They are the prayer of the whole Christ: Head and members, though prayed diversely by each according to the content of the psalm, whether penitential, petitionary, or praising.
When praying the liturgy of the hours, I try to be mindful of the fact that I am praying in union with the whole body of believers, united with Christ our Head. I try to do so, not only at the time of the specific petitions, but throughout the praying of the psalm. When praying alone, I modify the invocation: "O God, come to our assistance; o Lord, make haste to help us!"
Friday Lauds always begin with the great penitential psalm 51, in which we cry: "Create in me a clean heart, O God, cast me not away from your presence and take not your Holy Spirit from me."
The whole Christ prays today for and with Philip Seymour Hoffman.