The extent of the corpus of céli Dé texts has never been properly defined. There are ten or so works that most scholars who have commented upon them agree were authored by céli Dé, but as many as two dozen more texts that have occasionally been associated with them in some, usually imprecise, way. Remarkably, previous discussions of céli Dé texts – specifically those of Kenney, Flower, Hughes, and O'Dwyer – have largely neglected manuscript history as a means of elucidating textual authorship, origin, and relationships, and identifying céli Dé writings. One need only look to Richard Sharpe's Medieval Irish Saints' Lives for an example of the importance of the manuscript tradition in the evaluation of a primary source. The present chapter offers a manuscript-centred re-evaluation of the works that scholars have at various times associated with céli Dé, with the aim of identifying those texts that we may reasonably rely upon in our effort to determine who and what céli Dé were. It aims to be as complete as possible, but does not claim to be exhaustive or final. A catalogue of the texts examined here is provided in the Appendix.

Before continuing further, we must ask on what grounds we can identify something as a céli Dé text. A seemingly straightforward answer springs to mind – a céli Dé text is something written by a céle Dé. This in turn leads us to ask: what exactly is a céle Dé and what is the basis for identifying someone as such? However, since the purpose of this study is to provide the basis for a revised understanding of céli Dé, we are in danger here of circular thinking.