In historical study there are two types of literature. Secondary sources are written based on the original writings which are known as Primary sources. If you want to lern about the earliest Roman Emperors this source is indispensable. True, some of it is not historical and Suetonius is somewhat of a gossip monger at times, seeing as he explains in detail the various sexual appetites of each Caesar as well as other deviant behaviour. Still, this is one of the foremost primary sources about those famous Romans and most of the history books written on the Caesars are standing on Suetonius shoulders. Not much is known about the life of Gaius Suetonius Tranquillis. He was probably born in A.D. 69--the famous year of four Emperors--when his father, a Roman knight, served as a colonel in a regular legion and took part in the Battle of Baetricum.
Suetonius became a scribe and noted secretary to the military set, eventually ending up in the service of Hadrian, who was emperor from A.D. 117-138. He was dismissed for indiscreet behaviour with Hadrians empress, Sabina, but not before doing sufficient research to complete many books of a historical nature. His attempts at philosophy were much less well received, and most of his history has been overlooked by all but classical scholars, but this work, The Twelve Caesars has held the imagination of more than just the scholarly set since it was first written.
Suetonius had the good fortune of speaking to eyewitnesses from the time of the early Caesars. Much of his information about Tiberius, Caligula, Claudius, and Nero in fact comes from those who observed and/or participated in their lives. Suetonius is in many ways more of a reporter than an historian--he would record conflicting statements without worrying about the reconciliation (this set him apart from Tacitus and other classical historians who tried to find a consistency in stories and facts.
Suetonius has been described as the tabloid journalist of ancient Rome, because not only did he not appear to check facts (which in fact is not true--he did check, he just didnt try to smooth over the conflicting facts), but he choose to concentrate on the private lives, motivations and personality quirks of his subjects rather than their grand plans, policies and military/political victories. Thus, many details of the lurid scene appear. Suetonius, and this volume in particular, formed much of the basis for Robert Graves as he wrote I, Claudius and Claudius the God, which in turn pulled up the popularity of Suetonius in this generation.
Suetonius had first hand knowledge of many of the Caesars who followed the Claudians, and ready access to the archives of the imperial family and the Senate, given his imperial posting.
For the record, the twelve Caesars, about whom Suetonius writes, are: Julius Caesar, Augustus, Tiberius, Gaius Caligula, Claudius, Nero, Galba, Otho, Vitellius, Vespasian, Titus, Domitian
Suetonius held nothing back in writing about the personal habits of the emperors and their families, nor did he hold back in his moral judgement of them. Of Tiberius, for instance, he wrote that Tiberius did so many other wicked deeds under the pretext of reforming public morals--but in reality to gratify his lust for seeing people suffer--that many satires were written against the evils of the day, incidentally expressing gloomy fears about the future.... At first Tiberius dismissed these verses as the work of bilious malcontents who were impatient with his reforms and did not really mean what they said. He would remark: Let them hate me, so long as they fear me! But, as time went on, his conduct justified every line they had written.
Take a step back into the seemier side of ancient Rome, the side most history courses overlook in favour of more traditional historical events, and get this book!