A member of a religious sect that was excommunicated by the Vatican at the turn of the century, Josephus du Lac wrote a book of rituals and spells of unspeakable evil. A theologian and a mathematician, Josephus wrote the book in a Latin so archaic that only the sect members could understand it. They used an invention that Josephus created called "The Du Lac Cross" which would enable them to understand certain mystical texts and decipher hidden meanings within the book.

Fearing that the book would fall into the wrong hands, Josephus destroyed every cross except the one that was buried with him…right here in Sunnydale in a reliquary (which is normally used to house items of religious significance).

One of the rituals contained in the book was to enable a weak and sick vampire to be restored back to life. The ritual required the presence of the sick vampire's sire and must take place in a church on the night of the new moon.