Page "Antipope" Paragraph 1

In the list of popes given in the Holy See's annual directory, Annuario Pontificio, the following note is attached to the name of Pope Leo VIII ( 963 – 965 ): At this point, as again in the mid-eleventh century, we come across elections in which problems of harmonising historical criteria and those of theology and canon law make it impossible to decide clearly which side possessed the legitimacy whose factual existence guarantees the unbroken lawful succession of the successors of Saint Peter.

The uncertainty that in some cases results has made it advisable to abandon the assignation of successive numbers in the list of the popes.