ABSTRACT
Readers who have consulted Codex Usserianus Primus in Dublin, Trinity College Library MS 55, may have noticed on the inside front cover of its modern binding a note in pencil listing certain 'folios with style writing'. Unlike the manuscript itself, this note has a readily identifiable locus, tempus and persona - the long tenure of William O' Sullivan as Keeper of Manuscripts at Trinity College. And the causa scribendi must surely be his lifelong interest, both as curator and scholar, in Ireland's oldest manuscripts.1
