Making a special case for the young, illiterate children who saw a vision of the Virgin Mary in 1917, Pope Francis is in Portugal as they are declared saints. Thousands greeted him at the holy site of Fatima.
Pope Francis has cautioned against tales of near-daily visions but he said the case of Fatima was altogether different. He is in central Portugal to celebrate the centenary of the apparitions and canonize two of the three shepherd children.
In his evening prayer, Pope Francis said God's mercy was made real when a "Lady robed in white" appeared to the young children and confided her secrets of love and peace to them.
"As a bishop robed in white, I call to mind all those who ... desire to live in God and tell the mysteries of Christ in order to obtain peace," he said.
In May 1917, three young cousins aged 7-10, reported they had seen a vision of the Virgin Mary as they grazed their sheep. In the following months they said they received messages from her, including the "miracle of the sun" when the "spinning" of the sun was predicted to them as a miracle.
The children reported that the Madonna revealed to them three "secrets," and urged them to pray for peace and turn away from sin. The events happened as the 1914-1918 World War One was moving towards its end in Europe. One of the secrets is believed to have been the foretelling of the 1981 assassination attempt on St John Paul II, and the persecution of other Christians.
As Pope Francis celebrated an evening prayer in Fatima at the chapel built on the site of the apparitions, he encouraged the hundreds of thousands who had come to hear him to follow in the footsteps of the young shepherds and spread peace even in times of war.
"We will tear down all walls and cross every frontier, as we go out to every periphery, to make known God's justice and peace," he said.
Cardinal Pietro Parolin, Pope Francis' deputy, has said the importance of Fatima lies in the fact that poor, illiterate children were able to convey a message of love and forgiveness at a time of war, when "the talk was of hatred, vendetta, hostilities."
The two children who are to be beatified on Saturday, Francisco and Jacinta Marto, died of influenza two years after the visions. Lucia, who later became a nun and wrote of the children's experiences, died in 2005. The procedure to make her a saint could only begin at that time.
jm/kl (AFP, AP, LUSA, dpa)