The encyclopedic character of the _Etymologies_ may best be realized by a general view of its contents. The titles of the twenty books into which it is divided are as follows: Etymologiarum Libri XX. 1. de grammatica. 2. de rhetorica et dialectica. 3. de quattuor disciplinis mathematicis. 4. de medicina. 5. de legibus et temporibus. 6. de libris et officiis ecclesiasticis. 7. de Deo, angelis, et fidelium ordinibus. 8. de ecclesia et sectis diversis. 9. de linguis, gentibus, regnis, militia, civibus, affinitatibus. 10. vocum certarum alphabetum. 11. de homine et portentis. 12. de animalibus. 13. de mundo et partibus. 14. de terra et partibus. 15. de aedificiis et agris. 16. de lapidibus et metallis. 17. de rebus rusticis. 18. de bello et ludis. 19. de navibus, aedificiis et vestibus. 20. de penu et instrumentis domesticis et rusticis. To the modern reader, familiar with the names of only the modern sciences, this series of titles, which includes an almost complete list of the ancient sciences, may not be very illuminating. For this reason it is perhaps allowable to translate them, where it is possible to do so, into their modern equivalents. Thus we have grammar (Bk. 1), rhetoric and logic (Bk. 2), arithmetic, geometry, music, astronomy (Bk. 3), medicine (Bk. 4), law and chronology (Bk. 5), theology (Bks. 6–8), human anatomy and physiology (Bk. 11), zoölogy (Bk. 12), cosmography and physical geography (Bks. 13–14), architecture and surveying (Bk. 15 and part of Bk. 19), mineralogy (Bk. 16), agriculture (Bk. 17), military science (Bk. 18). This partial enumeration of the subjects treated in Isidore’s _Etymologies_ forms an imposing array, and serves to explain something of the importance of the work in the history of thought. The secret of this inclusiveness lay, however, not in an expanded, but in a contracted interest. Although Isidore is not surpassed in comprehensiveness by any one of the line of Roman encyclopedists who preceded him, in the quality of his thought and the extent of his information he is inferior to them all. Secular knowledge had suffered so much from attrition and decay that it could now be summarized in its entirety by one man.