The so-called “Book of Miracles II” that accompanies Þorláks saga helga in modern editions cites as a source a collection of visions about Bishop Þorlákur in Latin, written by Gunnlaugur Leifsson, a monk at Þingeyrar. The same lost work seems to have contained the original Latin text of “The Vision of Brestir”, translated in the D-redaction of Óláfs saga Tryggvasonar en mesta and preserved in Flateyjarbók (GKS 1005 fol.). The present paper offers further discussion of this Icelandic Latin work by suggesting that Gunnlaugur's collection of visions (which may be referred to as *Revelaciones Thorlaci episcopi) was included in the “brief” presented to the Icelandic General Assembly in the summer of 1198 by Ormr, chaplain to Bishop Brandr Sæmundarson of Hólar, and that it was this document that prompted Bishop Páll Jónsson of Skálholt to allow invocations to St Þorlákur and to have his bones translated and enshrined.