(VIS) This morning, on the Solemnity of Pentecost, Pope Benedict XVI presided at Mass in St. Peter's Square. The Mass, concelebrated by several Cardinals, was attended by tens of thousands of people, many of whom had participated in yesterday's meeting between the Pope and ecclesial movements and new communities.

"On the day of Pentecost," said the Pope in his homily, "the Holy Spirit descended powerfully upon the Apostles; and thus the Church's mission in the world began. Jesus Himself had prepared the Eleven for this mission, appearing to them a number of times after His resurrection. ... Remaining together was the condition placed by Jesus for receiving the gift of the Holy Spirit."

"This provides a remarkable lesson for all Christian communities. Sometimes, it is thought that missionary success depends principally on careful planning, followed by clever implementation through concrete commitment. Of course, the Lord asks our collaboration, but prior to any response on our part His initiative is necessary. His Spirit is the true protagonist of the Church."

Benedict XVI then commented on the images (of wind and fire) with which St. Luke describes "the irruption of the Holy Spirit." Images that recall the covenant of God with the People of Israel in the Sinai Desert and through which the Evangelist presents "Pentecost as the new Sinai, as the feast of the new pact, in which the Covenant with Israel is extended to all the people of the earth."

For this reason, "the Church was Catholic and missionary from her inception. The universality of salvation is significantly highlighted in the list of ethnic groups who listened to the first announcement of the Apostles. The People of God ... was enlarged ... until it no longer knew frontiers of race, culture, space or time. Unlike what happened in the Tower of Babel - when men, intent on building a way to heaven with their own hands, ended up by destroying their capacity to understand one another - in the Pentecost the Spirit, with the gift of tongues, shows how His presence unites and transforms confusion into communion. ... The Holy Spirit ... rebuilds the bridge of true communication between earth and heaven. The Holy Spirit is Love."

However, in order to know "the mystery of the Holy Spirit," we must go back to Jesus' words at the Last Supper, when the Apostles were disconcerted and saddened by His announcement of His death and departure.

"In order to comfort them [Jesus] explains the meaning of His leaving: He will go, but will return, in the meantime He will not abandon them, He will not leave them orphans. He will send the Counselor, the Spirit of the Father, and it will be the Spirit Who makes it known that Jesus' work is a work of love: the love of He Who offered Himself, the love of the Father Who gave Him."

"This is the mystery of Pentecost," said the Holy Father, "the Holy Spirit illuminates the human spirit and, revealing Christ crucified and risen, indicates the way to become like Him, to be, that is, 'image and instrument of the love which flows from Christ'."

After the Mass, Benedict XVI prayed the "Regina Coeli" with those present, before reflecting further upon Pentecost which, he reiterated, "invites us to return to the origins of the Church." He also quoted the words of the Apostolic Constitution "Lumen gentium" where it is written: "The Church, which the Spirit guides in way of all truth and which He unified in communion and in works of ministry, He both equips and directs with hierarchical and charismatic gifts and adorns with His fruits."

The Holy Father concluded: "Among the things prompted by the Spirit in the Church are the ecclesial movements and communities, which yesterday I had the joy of meeting in this square, in a great international meeting. All the Church, as Pope John Paul II used to like to say, is one great movement animated by the Holy Spirit, a river crossing history to irrigate it with the grace of God and render it fruitful of life, goodness, beauty, justice and peace."