The principate of the emperor Tiberius was a surprisingly interesting period in Roman library history. Devoted to books and scholarship himself, Tiberius built what must have been a very large new library, but he also confirmed the Augustan principle of constructing numerous separate structures rather than one comprehensive library. He invented the position of library commissioner, to which he appointed a scholarly advisor, not an administrator. He gave texts of three Greek authors to the libraries. This implies that those works had not previously been in the collection and so gives us valuable insight into the contents of the Augustan libraries.