Árni Magnússon’s rearrangement of paper manuscripts draws attention to the early history of Árni Magnússon’s (1663-1730) manuscript collection. The thesis examines Árni’s extensive rearrangement of paper manuscripts, showing that he repeatedly altered the physical composition of codices in his collection. The study is codicological in nature and investigates the frequency of rearrangements, Árni’s working procedure and the rationale behind his custodial changes.
The analysis shows that, for the time period investigated, the majority of manuscripts in the Arnamagnæan Collection have been altered. Árni’s work procedure was designed to enable the aggregation of copies of different origin and content as well as continual re-adjustment of the individual manuscripts. Árni’s rearrangement of manuscripts manifests itself in a variety of patterns, but in most cases, his aim was to facilitate scholarly work with the source material.

On the whole, Árni created a flexible library in which the physical form of the manuscripts was subject to his personal needs and changing preferences.The thesis provides the first coherent description of Árni's rearrangement of manuscripts and allows a more nuanced understanding of the rather complex early history of the Arnamagnæan Collection as well as the present-day form of many of its manuscripts.