In style and presentation Procopius frequently followed the classical historians, especially Herodotus and Thucydides. In spite of his dependence upon the Old Greek language of the ancient historians, and in spite of some artificiality of exposition, Procopius had a figurative, lucid, and vigorous style. He wrote three main works. The largest of these is The History in Eight Books, containing accounts of Justinian's wars with the Persians, Vandals, and Goths as well as accounts of many other sides of government life. The author spoke of the Emperor in a slightly laudatory tone, but in numerous instances he expresses the bitter truth. This work may be called a general history of Justinian's time. The second work of Procopius, On Buildings, is an unmitigated panegyric of the Emperor, probably written at his command, the main object of which is to give an account and description of the multitude of edifices erected by Justinian in all parts of his vast empire. In spite of rhetorical exaggerations and excessive praise, this work contains an abundance of geographical, topographical, and financial material, and serves therefore as a valuable source in the study of the social and economic history of the Empire. The third work of Procopius, Anecdota, or The Secret History (Historia Arcana), is distinctly different from the other two. It is a vicious libel upon the despotic rule of Justinian and his wife Theodora in which the author flings mud not only at the imperial couple but also at Belisarius and his wife, and in which Justinian is represented as the author of all the misfortunes which occurred in the Empire during this period. The contrast between this work and the other two is so striking that some scholars began to question the authenticity of The Secret History, for it seemed impossible that all three works had been composed by one and the same man. Only after a careful comparative study of The Secret History with all other sources pertaining to Justinian's epoch was it definitely decided that the work was really an authentic work of Procopius. When properly used, this work serves as an extremely valuable source on the internal history of the Byzantine Empire in the sixth century. Thus, all the works of Procopius, in spite of their exaggerations of the virtue or vice of Justinian's deeds, constitute a highly significant contemporary source for a closer acquaintance with the life of the period. But this is not all. Slavonic history and Slavonic antiquity find in Procopius invaluable information about the life and beliefs of the Slavs, while the Germanic peoples gather from him many facts about their early history.