A secret, divided in three parts (thus, known as the "three secrets") was entrusted by Our Lady to the three shepherds, and kept in writing by Sr. Lucia, who became a Carmelite nun.
The first two parts were revealed in 1941 by Sr. Lucia in a letter to the then Bishop of Leiria-Fatima.
This is the translation of Lucia's original letter in Portuguese:
"Well, the secret is made up of three distinct parts, two of which I am now going to reveal.
The first part is the vision of hell.
Our Lady showed us a great sea of fire which seemed to be under the earth. Plunged in this fire were demons and souls in human form, like transparent burning embers, all blackened or burnished bronze, floating about in the conflagration, now raised into the air by the flames that issued from within themselves together with great clouds of smoke, now falling back on every side like sparks in a huge fire, without weight or equilibrium, and amid shrieks and groans of pain and despair, which horrified us and made us tremble with fear. The demons could be distinguished by their terrifying and repulsive likeness to frightful and unknown animals, all black and transparent. This vision lasted but an instant. How can we ever be grateful enough to our kind heavenly Mother, who had already prepared us by promising, in the first Apparition, to take us to heaven. Otherwise, I think we would have died of fear and terror.
We then looked up at Our Lady, who said to us so kindly and so sadly:
â€śYou have seen hell where the souls of poor sinners go. To save them, God wishes to establish in the world devotion to my Immaculate Heart. If what I say to you is done, many souls will be saved and there will be peace."
In the second part of the secret, Sr. Lucia wrote:
"The (I World) war is going to end: but if people do not cease offending God, a worse one will break out during the Pontificate of Pius XI. When you see a night illumined by an unknown light, know that this is the great sign given you by God that he is about to punish the world for its crimes, by means of war, famine, and persecutions of the Church and of the Holy Father. To prevent this, I shall come to ask for the consecration of Russia to my Immaculate Heart, and the Communion of reparation on the First Saturdays. If my requests are heeded, Russia will be converted, and there will be peace; if not, she will spread her errors throughout the world, causing wars and persecutions of the Church. The good will be martyred; the Holy Father will have much to suffer; various nations will be annihilated. In the end, my Immaculate Heart will triumph. The Holy Father will consecrate Russia to me, and she shall be converted, and a period of peace will be granted to the world."