Louis Duchesne concluded that the Leonine book is a private collection of prayers copied without much intelligence from the official books at Rome about the year 538. He arrives at this date especially through an allusion in the Secret of a Mass placed in June (but really an Easter Mass), which refers to a recent deliverance from enemies. This allusion he understands to refer to the raising of the siege of Rome by Vitiges and his Goths at Easter-time, 538. Another writer attributed the allusion to Alaric's invasion in 402, and held that the compilation was made between 366 and 461. Another considered that the book was composed under Pope Felix III (483-492). Yet another suggests that the book is a compilation of Roman Masses made in the sixth or seventh century for use in Gaul, so that the composers of Roman books who were at that time introducing the Roman Rite into Gaul might have a source from which to draw their material. He suggests Gregory of Tours (died 594) as possibly the compiler.