The subject is a large one, and in the treatment of it, from considerations of space, it is necessary to omit some of the less important aspects. The main purpose of this article is to show reason for thinking that the estimate generally prevalent of Tacitus as a historian is unreasonably high, and that the brilliance of his style dazzles the eyes of his readers and blurs them to imperfect consciousness of his many great defects. There are three great Roman writers, born within a space of twenty years, who strongly resemble each other in their general outlook upon the Roman state, and whose power of emitting epigrams of a biting, penetrating and even savage character is much the same. These are Lucan, Tacitus and Juvenal. All of them deal with history. There is the same ‘saeva indignatio’ gnawing at the hearts of all the trio. They write as though they were living in the worst of all possible worlds. All three look back with longing eyes on the great glories of the old Republic. All have a feud with the gods, who take so little care for mankind as to impose upon them the inexorable dominance of the imperial system. All three again feel that the Romans of their day are degenerate and corrupt. It may be reasonably said that the combination of pessimism with a capacity for savage epigram is not a promising equipment for the historian. Tacitus was saner than Swift, but if Swift had written the history of our great rebellion and of the reign of Charles the Second we should doubtless have found many points of comparison between him and the great Roman. Napoleon showed a sound instinct when he described Tacitus as ‘the detractor of humanity.’