On August 13, the day the fourth apparition was to take place, the seers were not at Cova da Iria.
They had been abducted by the mayor of Vila Nova de Ourém, who attempted to force from them the secret revealed in the apparition of July 13. The children held fast despite the mayor imprisoning them, and threatening to plunge them in boiling oil.
At Cova da Iria, thunder, followed by lightning, was heard at the usual time.The spectators noticed a small white cloud that hovered over the holm oak for a few minutes. Phenomena of coloration were observed on the faces of the people, the clothing, the trees, and the ground.
Our Lady had certainly come, but she had not found the seers.
On August 19, at about four o'clock in the afternoon, Lucia was with Francisco and another cousin at Valinhos, a property belonging to one of her uncles, when the atmospheric changes that preceded the apparitions of Our Lady at Cova da Iria began to occur: a sudden cooling of the temperature and a waning of the sun.
Feeling that something supernatural was approaching and enveloping them, Lucia sent for Jacinta, who arrived in time to see Our Lady appear – heralded as before by a bright light – over a holm oak slightly larger than the one at Cova da Iria.
Lucia: What does Your Grace wish of me?
Our Lady: I want you to continue to go to Cova da Iria on the thirteenth of each month and to continue to pray the Rosary every day. On the last month, I will perform the miracle for all to believe.
Then Our Lady’s face became more serious, and even upset.
Our Lady: If they had not taken you to Ourém, the miracle would have been even greater.
Lucia: What does Your Grace want done with the money that the people leave at Cova da Iria?
Our Lady: Have two portable stands made. You and Jacinta with two other girls dressed in white carry one of them, and let Francisco carry the other one with three other boys. The portable stands are for the feast of Our Lady of the Rosary. The money that is left over should be contributed to the chapel that they shall build.
Lucia: I would like to ask you for the healing of some sick persons.
Our Lady: Yes, I will cure some during the year.
Becoming sadder, she recommended anew the practice of mortification, saying lastly, 'Pray, pray much, and sacrifice for sinners, for many souls go to hell because there is no one to sacrifice and pray for them.'
As usual, she then began to rise toward the east. The seers cut boughs off the tree over which Our Lady had appeared to them and took them home. The boughs gave off a uniquely sweet fragrance.
Read: Fifth Apparition