The Collective Knowledge (referred to as the Black Book by Chris and Alex) is a religious text written by The Order. Scans of the book's pages can be downloaded here. A transcript of the book's contents can also be found here.
The Collective Knowledge details the beliefs of The Order as well as their knowledge of Rifts, their history, laws, hierarchy, and known information about their god. The book is known to have been updated over the years, most notably with the Oracle's prophecies, as the first Collective Knowledge was written in the early 1900s when the organization was formed. Each member of The Order is seemingly given a copy of the Collective Knowledge upon joining; reacquiring copies of the book that belonged to deceased members or defectors seems to be a priority for the organization.
Kind von der Ritter led Chris, Alex, and Jesse Laurenzi to the location of a copy of the Collective Knowledge shortly after Greg Benson's death. Having taken the book from said location, they then uploaded scans of its contents to the internet. The Order later took the book from Chris, along with military documents he had obtained from a chest, when they broke into his home and stabbed him. The initials found within the particular copy of the book taken from Chris suggest that it once belonged to Marc McComber.