Not much is known about the life of Gaius Suetonius Tranquillus. 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. From the letters of Suetonius's close friend Pliny the Younger we learn that he practised briefly at the bar, avoided political life, and became chief secretary to the Emperor Hadrian (A.D. 117-138). The historian Spartianus records that he was one of several Palace officials, including the Guards Commander, whom Hadrian, when he returned from Britain, dismissed for behaving indiscreetly with the Empress Sabina. Suetonius seems to have lived to a good age. The titles of his books are recorded as follows: The Twelve Caesars; Royal Biographies; Lives of Famous Whores; Roman Manners and Customs; The Roman Year; Roman Festivals; Roman Dress; Greek Games; Offices of State; Cicero's Republic; The Physical Defects of Mankind; Methods of Reckoning Time; An Essay on Nature; Greek Objurgations; Grammatical Problems; Critical Signs Used in Books. But apart from fragments of his Illustrious Writers, which include short biographies of Virgil, Horace, and Lucan, the only extant book is The Twelve Caesars, the most fascinating and richest of all Latin histories.
Suetonius was fortunate in having ready access to the Imperial and Senatorial archives and to a great body of contemporary memoirs and public documents, and in having himself lived nearly thirty years under the Caesars. Much of his information about Tiberius, Caligula, Claudius, and Nero comes from eye-witnesses of the events described. Apparently he took care to check facts wherever possible, and often quotes conflicting evidence without bias, which was not the habit of Tacitus or other later historians. If his credulousness about omens and prodigies is discounted, he seems trustworthy enough, his only prejudice being in favour of firm mild rule, with a regard for the human decencies. As the nineteenth-century Cambridge historian George Long wrote:
His language is very brief and precise, sometimes obscure, without any affectation or ornament. He certainly tells a prodigious number of scandalous anecdotes about the Caesars, but there was plenty to tell about them; and if he did not choose to suppress those anecdotes which he believed to be true, that is no imputation on his veracity. As a great collection of facts of all kinds, his work on the Caesars is invaluable...
And Pliny, who persuaded the Emperor Trajan to grant Suetonius the immunities usually granted only to a father of three children; though he had none, wrote that the more he knew of Suetonius, the greater his affection for him grew; I have had the same experience.
This version of The Twelve Caesars is not intended as a school crib; the genius of Latin and the genius of English being so dissimilar that a literal rendering would be almost unreadable. For English readers Suetonius's sentences, and sometimes even groups of sentences, must often be turned inside-out. Wherever his references are incomprehensible to anyone not closely familiar with the Roman scene, I have also brought up into the text a few words of explanation that would normally have appeared in a footnote. Dates have been everywhere changed from the pagan to the Christian era; modern names of cities used whenever they are more familiar to the common reader than the classical ones; and sums in sesterces reduced to gold pieces, at 100 to a gold piece (of twenty denarii), which resembled a British sovereign. The problem of finding suitable English equivalents for Latin technical words is exemplified in Imperator. This, at first, meant simply 'army commander'; next it became a title of honour which a general might earn by an important victory; then it was placed as a title of honour after, or (more flatteringly) before, the name of one of the ruling Caesars, whether or not he had won any victories; finally, it was used in an absolute sense to mean 'Emperor'.