-- Rom 4:13, 16-18
"Christ, sent by the Father, is the source of the Church's whole apostolate"; thus the fruitfulness of apostolate for ordained ministers as well as for lay people clearly depends on their vital union with Christ. In keeping with their vocations, the demands of the times and the various gifts of the Holy Spirit, the apostolate assumes the most varied forms. But charity, drawn from the Eucharist above all, is always "as it were, the soul of the whole apostolate."
-- CCC 864