Procopius of Caesarea, who accompanied the Roman general Belisarius in the wars of the Emperor Justinian, became the principal historian of the 6th century. Whilst alive, his books were in favour of Justinian, but this book, written for posthumous publication and not discovered until centuries later, is not only really critical of Justinian, but portrays him as some sort of demon. The accounts in this book sound farfetched, but are considered genuine (albeit not accurate) by modern historians.