Papal Bull

Papal Bull, special letter or document bearing the pope's own seal. The word bull originally meant “seal” in the Middle Ages; it was applied also to the document to which the seal was affixed. Application of the word exclusively to papal documents, as opposed to documents of state bearing the seal of a sovereign, is a relatively modern development.

The papal seal affixed to most bulls is made of lead and is inscribed with the name of the reigning pope on one side and representations of the heads of St. Peter and St. Paul on the other side. A golden seal, or bulla aurea, is attached to papal documents of special gravity. A decree of Pope Leo XIII in 1878 made it permissible to use red stamps in place of seals for ease in mailing. Another of Leo XIII's innovations was the substitution of Roman script for the archaic Gothic script used by previous popes. Until the 11th century papal bulls were written on papyrus; thereafter they were written on parchment.