2 Now We have earnestly striven, by the help of His grace, to follow theexample of Christ, Our Saviour, the Prince of Pastors, and the Bishop of ourSouls, by diligently carrying on His office, entrusted by Him to the Apostlesand chiefly to Peter, "whose dignity faileth not, even in his unworthysuccessor" (St. Leo the Great, Sermon ii., On the Anniversary of hisElection). In pursuance of this object We have endeavoured to direct all that Wehave attempted and persistently carried out during a long pontificate towards two chief ends: in the first place, towards the restoration, both in rulers and peoples, of the principles of the Christian life in civil and domestic society, since there is no true life for men except from Christ; and, secondly, to promote the reunion of those who have fallen away from the Catholic Church either by heresy or by schism, since it is most undoubtedly the will of Christ that all should be united in one flock under one Shepherd. But now that We are looking forward to the approach of the closing days of Our life, Our soul is deeply moved to dedicate to the Holy Ghost, who is the life-giving Love, all the work We have done during Our pontificate, that He may bring it to maturity and fruitfulness. In order the better and more fully to carry out this Our intention, We have resolved to address you at the approaching sacred season of Pentecost concerning the indwelling and miraculous power of the Holy Ghost; and the extent and efficiency of His action, both in the whole body of the Church and in the individual souls of its members, through the glorious abundance of His divine graces. We earnestly desire that, as a result, faith may be aroused in your minds concerning the mystery of the adorable Trinity, and especially that piety may increase and be inflamed towards the Holy Ghost, to whom especially all of us owe the grace of following the paths of truth and virtue; for, as St. Basil said, "Who denieth that the dispensations concerning man, which have been made by the great God and our Saviour, Jesus Christ, according to the goodness of God, have been fulfilled through the grace of the Spirit?" (Of the Holy Ghost, c. xvi., v. 39).
Source: Divinum Illud Munus (Vatican.va)