14 Lastly, I am writing with my own hand that which you alone may read. As I hope that the Lord will deliver me from all troubles, I have been warned, not by man, nor through man, but plainly by Himself that this is forbidden me. For when I was anxious, in the very night in which I was preparing to set out, you appeared to me in a dream to have come into the Church, and I was not permitted to offer the sacrifice. I pass over other things, which I could have avoided, but I bore them for love of you, as I believe. May the Lord cause all things to pass peaceably. Our God gives warnings in many ways, by heavenly signs, by the precepts of the prophets; by the visions even of sinners He wills that we should understand, that we should entreat Him to take away all disturbances, to preserve peace for you emperors, that the faith and peace of the Church, whose advantage it is that emperors should be Christians and devout, may continue.
Source: Letters (New Advent)