The Secretariat of State is a body of the Roman Curia that is closely linked to the heart of the papacy, insofar as it operates in direct union with the pope and makes his wishes a reality. Studying its development is helpful for identifying the evolution of the policies of the popes and, above all, the evolution of the institution of the papacy. The more the papacy assumes a central role in Catholicism, the more it requires effective political offices. Thus, the Secretariat of State constitutes that key uniting feature between the will of the pope and the structure of the Roman government, local churches, and national governments. The history of the Secretariat of State is an institutional history and a history of its members; it is a history that can be properly understood from the perspective of religious history; it is a history of the ideas and power within the Church.

Nepotism is a way to organize ecclesiastical power relations, in particular those of the papacy, under the conditions of celibacy on the basis of family relations. In the long run, however, the micro-policy of family was replaced by the micro-policy of bureaucracy, the cardinal-nephew by the secretary of state. But for more than a thousand years, family networks were the most reliable foundation of papal domination. On the other hand, therefore, massive maintenance of the pope’s family interest was a necessary consequence. For some time between the sixteenth and seventeenth centuries, Roman nepotism even became an established quasi-institution, halfway between loosely structured family network and neutral Church bureaucracy. The papal system of government was stabilized through circular dependency of electors and elected heads, of cardinals and popes.