This Visigothic manuscript has been conserved in the Library of the University of Santiago de Compostela, catalogued as Ms. 609 (Reserv. 1), since the middle of the last century. Its name has varied over the course of time: it formerly had a flyleaf giving its title as the Prayer Book of Ferdinand I, and scholars referred to it by this name until recently, when it became known as the Ferdinand I Book of Hours, which better reflects its contents Since it is an exceptionally fine book, it has appeared in several exhibitions, and there are a number of descriptions in the corresponding catalogues.
It has served as a base for biblical and liturgical studies and has always been seen as a reference for the highest standard of work of scriptoriums of the mid 11th century, and much admired by art experts.
The manuscript as it survives today is made up of 226 original regularly sized folios of 320 x 200 mm, though it is probable that the original measurements were 320 x 200 mm and that the sheets were trimmed during successive bindings. The sheets are numbered in pencil, from 1 to 224, with two irregularities in the pagination, since pages 37 and 199 each occur twice. This repetition was subsequently preserved by introducing 37 bis and 199 bis, a definitive pagination decided by a person unknown, at some time between 1900 and 1912. The manuscript was restored, for the first time as far as we can see, in 1973, when new front and back flyleaves in modern parchment were added.
Several folios have been lost, at least three of them cut out for reasons unknown. It is written in unbroken lines, the number of lines per page varying between 22 and 34.
The former binding included a double folio which though old was not contemporaneous with the manuscript, and this has also been conserved.
We have 1 facsimile edition of the manuscript "Ferdinand I Book of Hours": Libro de Horas de Fernando I de León facsimile edition, published by Testimonio Compañía Editorial, 1995