Christ summons the Church, as she goes her pilgrim way, to that continual reformation of which she always had need.
Coming forth fromthe eternal Father's love, founded in time by Christ the Redeemer, and made one in the Holy Spirit, the Church has a saving and an eschatological purpose which can be fully attained only in the future world. But she is already present in this world, and is composed of men, that is, members of the earthly city who have a call to form the family of God's children during the present history of the human race, and to keep increasing it until the Lord returns.
This she does most of all by her healing and elevating impact on the dignity of the person, by the way in which she strengthens the seams of human society and imbues the everyday activities of men with a deeper meaning and importance. Thus, through her individual memebrs and her whole community, the Church believes she can contribute greatly toward making the family of man and its history more human.
The two quotes above come from the documents of the Vatican II Council. They're quoted on page 72 of Robert Warren's On the Anvil.