1. Twenty-five years ago, on Dec. 4, 1963, the supreme pontiff Paul VI promulgated the constitution Sacrosanctum Concilium on the sacred liturgy, which the fathers of the Second Vatican Council, gathered in the Holy Spirit, had approved but a short time before.  It was a memorable event on several accounts. Indeed, it was the first fruit of the council, called by Pope John XXIII to update the Church. The moment had been prepared for by a great liturgical and pastoral movement, and was a source of hope for the life and the renewal of the Church.
In putting into practice the reform of the liturgy, the council achieved in a special way the fundamental aim which it had set itself: "To impart an ever increasing vigor to the Christian life of the faithful; to adapt more suitably to the needs of our own times those institutions that are subject to change; to foster whatever can promote union among all who believe in Christ; to strengthen whatever can help to call the whole of humanity into the household of the Church." 
2. From the beginning of my pastoral ministry in the See of Peter, I have taken care "to state the lasting importance of the Second Vatican Council," calling attention to "our clear duty to devote our energies to putting it into effect." Our efforts have been directed toward "bringing to maturity, in the sense of movements and of life, the fruitful seeds which the fathers of the ecumenical council, nourished with the word of God, cast upon the good soil (cf. Mt. 13:8, 23) that is, their authoritative teaching and pastoral decisions."  On several occasions I have developed various aspects of the conciliar teaching on the liturgy  and have emphasized the importance of the constitution Sacrosanctum Concilium for the life of the people of God: In it "the substance of that ecclesiological doctrine which would later be put before the conciliar assembly is already evident. The constitution Sacrosanctum Concilium, the first conciliar document, anticipated"  the dogmatic constitution Lumen gentium on the Church and amplified, in its turn, the teaching of the constitution.
After a quarter of a century, during which both church and society have experienced profound and rapid changes, it is a fitting moment to throw light on the importance of the conciliar constitution, its relevance in relation to new problems and the enduring value of its principles.