The celebrated Irish work called the _Leabhar Na g-Ceart_, or _Book of Rights_, has been generally attributed to St. Benignus, although there seems to be good reason for doubting if he was really its author, at least in its present form. The title or inscription of the book certainly attributes it to Benignus. It is to this effect: "The beginning of the _Book of Rights_, which relates to the revenues and subsidies of Ireland as ordered by Benen, son of Sescnen, Psalmist of Patrick, as is related in the _Book of Glendaloch_." The _Book of Glendaloch_ is no longer extant; but it seems clear from this very title that the work in its present form is derived from the ancient compilation known as the _Book of Glendaloch_, and which the Four Masters tell us was in their hands when composing their own immortal work. The copy in the _Book of Glendaloch_ may have been itself made from the original treatise on the subject by St. Benignus, who was in every way well qualified for the task, both by his literary training as well as by his knowledge of his native language, and his familiarity with the laws and customs of the various provinces. The title of the book very fairly describes its contents. It gives an exceedingly minute and interesting account of the revenues and rights of the supreme king; of the services and duties rendered to him by the provincial kings and inferior chiefs, as well as of the gifts and subsidies which he owed them in return. It gives also a full account of the revenues and rights of each of the provincial monarchs, and the services to be rendered to them by the sub-chiefs of the various districts, and the hereditary offices and honours held by the heads of the great families in the provincial assemblies. The work is partly in poetry and partly in prose; and although in its present form it cannot have dated from the time of St. Benignus, it is still an exceedingly valuable work as illustrating the internal organization of the entire kingdom, and its minor principalities, and may have been originally drawn up by that learned and holy man, with a view of preventing internecine feuds, by definitely and authoritatively fixing the rights and duties of the various princes and chiefs of the kingdom. This work has been translated and annotated for the Dublin Archæological Society by the late John O'Donovan. St. Benignus is said by Jocelin to have written also a life of St. Patrick, but no copy of it is now known to exist; and he has been always regarded as one of the compilers of the great collection of Brehon Laws known as the _Senchus Mor_.