Divine Mercy in my Soul PDF File
FOOTNOTE 3 I am to write  down the encounters of my soul with You, O God, at the moments of Your special visitations (Diary 6)
 During her stay in Vilnius, Sister Faustina was told by her confessor, Father Michael Sopocko, to write down her interior experiences.
When asked by someone in the Congregation why Sister Faustina had been writing a diary, Father Sopocko answered: “I was a professor at the Seminary and at the School of Theology of the Stefan Batory University in Vilnius at the time. I had no time to listen to her lengthy confessions at the confessional, so I told her to write everything down and then to show it to me from time to time. This is how the Diary came into being” (Father Sopocko’s letter of March 6, 1972).
Sister Faustina mentions the confessor’s order in numbers 6 and 839 of the Diary.
In addition to this order from her confessor, the Servant of God mentions, on many pages of her diary, a distinct command to write, given her by the Lord Jesus Himself (see diary nos. 372, 459, 895, 965, 1142, 1457, 1567, 1665, and others).