VATICAN CITY, APRIL 13, 2003 ( John Paul II entrusted the "four pillars of peace" to youth worldwide, and appealed for solidarity with their contemporaries who suffer from violence, especially in the Mideast.

During a solemn Palm Sunday Mass attended by more than 40,000 people in St. Peter's Square, the Pope pointed out to youth the foundations of the culture of peace -- truth, liberty, justice and love -- that were outlined in John XXIII's 1963 encyclical "Pacem in Terris."

"How can you not express fraternal solidarity to your contemporaries who are suffering from war and violence in Iraq, in the Holy Land, and in several parts of the world?" John Paul II asked during the homily, heard by numerous young people.

Today the Church observed the 18th World Youth Day at the diocesan level. It came in the wake of last July's international event in Toronto.

The Pope noted that Christ said he was the "King of truth, freedom, justice and love. These are the four pillars on which it is possible to construct the building of true peace, as Blessed John XXIII wrote 40 years ago in the encyclical 'Pacem in Terris.'

"I hand symbolically to you, young people of the whole world, this historic document, more important than ever. Read it, meditate on it, make every effort to put it into practice. Then you will be 'blessed,' because you will be real children of the God of peace."

"Peace is a gift of Christ, which he obtained for us with the sacrifice of the cross," John Paul II continued. "To achieve it effectively it is necessary to go up to Calvary with the divine Master. And who can lead us better in this ascent than Mary, who was given to us precisely as Mother, under the cross?"

"To help to discover this wonderful spiritual reality, I have chosen as the topic of the Message for World Youth Day this year the words of the agonizing Christ: 'Behold your Mother,'" the Holy Father continued.

Peace was also the topic of the Prayers of the Faithful, which were read after the Pope's homily.

One of the prayers, recited in Arabic, implored: "Let us pray for all peoples and cultures of the world, for all those who seek God in different religious ways. May there always be dialogue among them, may intolerance and contempt be extinguished, and together may they seek ways of concord and fraternity."