_Tacitus as a historian._--As regards his sources, Tacitus makes more use of his predecessors than he does of original documents. Among the latter he mentions _acta diurna_ (_Ann._ iii. 3) and _commentarii_ or _acta senatus_ (_Ann._ xv. 74); but these he did not make much use of, as they were apt to be falsified. He also refers to _publica acta_, probably inscriptions (_Ann._ xii. 24); Tiberius' speeches (_Ann._ i. 81); memoirs of Agrippina, Nero's mother (_Ann._ iv. 53); and of Domitius Corbulo on his campaigns in Parthia (_Ann._ xv. 16). He also refers by name to several historians, especially in dealing with the times after Nero, as C. Plinius (_Ann._ i. 69, quoted p. 284), Vipstanus Messalla (_H._ iii. 25), Fabius Rusticus,[114] and Cluvius Rufus[115] (_Ann._ xiii. 20). Other writers are sparingly mentioned, as Sisenna (_H._ iii. 51), Caesar (_Germ._ 28). It is certain that Tacitus made use of other historians, but he generally refers to his sources without mentioning names (as _Ann._ i. 29, 'tradunt plerique'). He sometimes weighs the value of two conflicting accounts, or mentions a story only to reject it. _Ann._ iv. 11, 'Haec vulgo iactata, super id quod nullo auctore certo firmantur, prompte refutaveris.' Tacitus' credibility has been attacked, particularly as regards his representation of the characters of Tiberius and Nero, but not very successfully. He has, however, made mistakes, the most striking of which are his view of the Christians (_Ann._ xv. 44) and his account of the Jews (_H._ v. 2 _sqq._). The explanation is that he held the view current in the upper classes, and did not take the trouble to investigate these matters, as the Jews and Christians belonged mostly to the lower orders. Tacitus is not free from superstition (_Ann._ xi. 21; _H._ ii. 50, etc.), but one must not suppose he believes the fables he relates (as _Ann._ vi. 28; _H._ iv. 83) simply because he expresses no opinion of them. Tacitus is free from party spirit (_Ann._ i. 1, 'sine ira et studio, quorum causas procul habeo'; cf. _H._ i. 1) and just in his judgment, except in a few passages in the _Histories_, where he is rather unfair (i. 42, ii. 95). He is milder in the _Annals_ through advancing years, and from the better times he lived in. Generally he takes a lenient view of things, except (1) in offences against the state (cf. the character of Tiberius); (2) when the religious element comes in; cf. what he says of Claudius' marriage with his brother's daughter Agrippina: _Ann._ xiv. 2, 'Agrippina ... exercita ad omne flagitium patrui nuptiis.' He shows a somewhat lax morality occasionally, as in _Ann._ xiii. 17 _sqq._, when speaking of Nero's murder of his brother Britannicus. In _Ann._ xi. 19 he approves of compassing a barbarian's death by treachery.