A second scribe, who wrote eleven leaves, signed himself Aonghus Ó Callanáin,[3][4] and was probably a member of a well-known family of medical scholars from West Cork.

The contents display thoughtful organisation, beginning with religious material mostly relating to the saints of Ireland (lives and anecdotes), including Patrick, Brigid, Colum Cille, Ciarán and Brendan,[5] but also incorporating the early medieval Teanga Bhiothnua ('Evernew tongue').

[6] Texts translated to Irish, broadly related to the religious theme, are found in this section also, and feature the Conquests of Charlemagne,[7] the History of the Lombards (a chapter from the Golden Legend),[8] and The Travels of Marco Polo.

The book also contains Crichad an Chaoilli, a topographical document, possibly from the 13th Century, describing the district between Mallow and Fermoy in terms of townlands, the names of many of which are still recognizable in the form of their present-day counterparts.

In its design and execution, and in its combination of native and European tradition, the book is a library of literature that makes a self-assured statement about aristocratic literary taste in autonomous Gaelic Ireland in the late 15th century.

[17] It is thought to be identical to a book confiscated by Lewis, 1st Viscount Boyle of Kinalmeaky, then aged 23, at the siege of Kilbrittain Castle in 1642 during the Irish Confederate Wars, and sent by him to his father, The 1st Earl of Cork.

In 1930, the manuscript was transferred permanently from Lismore to Chatsworth House in England, where it remained until 2020, except for the years 1939–48 when it was removed to safe storage during the Second World War and also made available for the creation of the facsimile published in 1950.