Of these the first was the one for which he was most highly qualified, and in which he gained his highest renown. His crowning work in this department was the _Antiquities Divine and Human_, in 41 books. [13] This was the greatest monument of Roman learning, the reference book for all subsequent writers. It is quoted continually by Pliny, Gellius, and Priscian; and, what is more interesting to us, by St Augustine in the fifth and seventh books of his _Civitas Dei_, as the one authoritative work on the subject of the national religion. [14] He thus describes the plan of the work. It consisted of 41 books; 25 of human antiquities, 16 of divine. In the human part, 6 books were given to each of the four divisions; viz. of Agents, of Places, of Times, of Things. [15] To these 24 one prefatory chapter was prefixed of a general character, thus completing the number. In the divine part a similar method was followed. Three books were allotted to each of the five divisions of the subject, viz. the Men who sacrifice, the Places, and Times of worship, [16] the Rites performed, and finally the Divine Beings themselves. To these was prefixed a book treating the subject comprehensively, and of a prefatory nature. The five triads were thus subdivided: the first into a book on _Pontifices_, one on Augurs, one on _Quindecimviri Sacrorum_; the second into books on shrines, temples, and sacred spots, respectively; the third into those on festivals and holidays, the games of the circus, and theatrical spectacles; the fourth treats of consecrations, private rites, and public sacrifices, while the fifth has one treatise on gods that certainly exist, one on gods that are doubtful, and one on the chief and select deities.