"Keep watch over yourselves and over the whole flock
of which the Holy Spirit has appointed you overseers,
in which you tend the Church of God
that he acquired with his own Blood.
I know that after my departure savage wolves will come among you,
and they will not spare the flock...
And now I commend you to God
and to that gracious word of his that can build you up
and give you the inheritance among all who are consecrated.
-- Acts 20:28-38
The Holy Spirit is "the principle of every vital and truly saving action in each part of the Body." He works in many ways to build up the whole Body in charity: by God's Word "which is able to build you up"; by Baptism, through which he forms Christ's Body; by the sacraments, which give growth and healing to Christ's members; by "the grace of the apostles, which holds first place among his gifts"; by the virtues, which make us act according to what is good; finally, by the many special graces (called "charisms"), by which he makes the faithful "fit and ready to undertake various tasks and offices for the renewal and building up of the Church."
-- CCC 798