Tacitus is remarkably confident in the analysis and interpretation of motive and causal sequence. Having made up his mind on a matter, he opens up with all the stylistic artillery he can muster. With one eye open for pretence, he is by no means reticent to take upon himself the responsibility for stripping away the pretence and revealing the intentions and state of mind of characters. This will be readily granted. Yet it is in fact notable how often he seems to depart from the practice of simply setting forth the results of his researches and interpretations as outright statement. He creates, as it were, a distance between himself and facts, suspicions, rumours, motives and the reports of his sources. This provokes a number of questions, dealt with here in three sections. First, there are instances where he appears to allow uncertainty, where he uses expressions alluding to report, varying from rumour to historical record: why and when does he do this? In the same vein, why and when does he cite authorities and among them why does he cite some by name, which he does so seldom? Second, there is a distinct, but connected, category of usage which presents alternatives of motive. Last, I will examine larger, thematic areas where techniques are combined.