Librarian of the Holy Roman Church. — This is the current title of the Cardinal entrusted with the high direction of the Vatican Library; to it is joined that of Archivist of the Holy Roman Church.
The first mention of a *bibliothecarius* in the papal curia dates to the year 781, in a document in which a certain Theophilus *biobiothecarius* appears as a witness; documents of dubious authenticity mention him even earlier, but it seems that until then the preservation of the acts of councils, the registers of letters, and in general the books forming the Pope’s library was the task of the head of the notaries, the *primicerius notariorum*. The *b.* took part in the work of the chancery alongside the notaries and the *iudices de clero*; among the various forms of his title, the most common was that of *bibliothecarius Sedis Apostolicae*. In the 11th century, his position in the chancery became prominent, and as a rule he was chosen from among the suburbicarian bishops; from 1037 to 1144, the same person often held the double title of *cancellarius et bibliothecarius*, which alludes to the dual function of drafting documents and preserving the Church’s records. Subsequently, the title of *b.* disappeared as an attribute of the head of the chancery; however, until the early years of the 13th century, the names of some *b.* appear among the *iudices*, who were by then no longer connected to II. At the same time, the ancient papal archive, along with the library, was dispersed.
The library reconstituted by Boniface VIII followed the Popes to Avignon and was entrusted there to the Dominican Francesco Tolomei, who held it until 1318; the office of *b.* was then given to the Augustinians.
With the foundation of the present Vatican Library by Nicholas V (1447–55), the character of the office changed, and from then on it was entrusted to scholars and learned men. Leo X appointed the first Cardinal *b.*, who carried out the office through one or two custodians. In the last century, the position was sometimes given to the Cardinal Secretary of State, who assumed its functions in case of vacancy; in recent times, the *b.* has been chosen from among cardinals particularly distinguished for learning.