The breakaway cardinals returned to Avignon, taking much of the administration with them. The Roman papacy adapted by imitating the type of letter called a ‘brief’ used by some secular systems. Briefs were written by a different set of men, and before long distinguished by humanistic script. From this time on a dual system operated: Chancery and Secretariate. Initially the latter was for high-level letters but in the later fifteenth century it took on routine business too. Another post-Schism innovation was the sale of offices. Apparently absurd, this bound the upper classes of Italy to the papacy. After the Council of Trent papal government was drastically reorganised. The book enters scantily researched territory in attempting to map the changes in the functioning of the Penitentiary, the processes behind the production of letters by the Chancery and of briefs by the secretaries, and at the Congregations of the Council and of the Inquisition. The documentation generated by these two-sub-systems on the problem of whether Calvinist baptism was valid (for example) is of a kind that medievalists can only envy.