There follows a collection of brief Isidorean prefaces to the books of Scripture. Then comes a curious book, which may have been suggested to the writer by the words of Augustine himself. This is the _Liber numerorum_, the book of the _numbers_ occurring in the Scriptures. It tells the qualities and mystical significance of every number from one to sixteen, and of the chief ones between sixteen and sixty. These numbers were “most holy and most full of mysteries” to Augustine,[125] and Augustine is the man whom Isidore chiefly draws on in this treatise--Augustine at his very worst. One might search far for an apter instance of an ecclesiastical writer elaborately exploiting the most foolish statements that could possibly be found in the writings of a great predecessor. Isidore composed a polemic treatise on the Catholic Faith against the Jews--_De fide Catholica contra Judaeos_. The good bishop had nothing to add to the patristic discussion of this weighty controversy. His book is filled with quotations from Scripture. It put the matter together in a way suited to his epoch and the coming centuries, and at an early time was translated into the German and other vernacular tongues. Three books of _Sententiae_ follow, upon the contents of Christian doctrine--as to God, the world, evil, the angels, man, Christ and the Church. They consist of excerpts from the writings of Gregory the Great and earlier Church Fathers.[126] A more original work is the _De ecclesiasticis officiis_, upon the services of the Church and the orders of clergy and laity. It presents the liturgical practices and ecclesiastical regulations of Isidore’s epoch. Isidore seems to have put most pious feeling into a work called by him _Synonyma_, to which name was added the supplementary designation: _De lamentatione animae_. First the Soul pours out its lament in excruciating iteration, repeating the same commonplace of Christian piety in synonymous phrases. When its lengthy plaint is ended, Reason replies with admonitions synonymously reiterated in the same fashion.[127] This work combined a grammatical with a pious purpose, and became very popular through its doubly edifying nature, and because it strung together so many easy commonplaces of Christian piety. Isidore also drew up a _Regula_ for monks, and a book on the Order of Creation has been ascribed to him. This completes the sum of his extant works upon religious topics, from which we pass to those of a secular character.