More than any other single rhetorical device in Latin oratory and literature, the sententia is the supreme expression of the self-image of Rome during the imperial period, the Principate. Whether one defines sententia as a generalizing maxim or a prose epigram, its importance in Roman rhetoric, literature, and public life during the early Principate indicates that it is a literary form intimately connected with the unique social code of that period. An illuminating example of the skillful use of sententiae is found in the Roman historian Tacitus's narration of the history of Emperor Tiberius (A.D. 14-37) in Books 1-6 of the Annales. The entire narration of Tiberius's principate in Annales 1-6 could be said to be sententious, in the sense that individual episodes or agents continually serve as opportunities for Tacitus to categorize people and events in the past and to formulate general "laws" that may be applicable to events in the future. Patrick Sinclair undertakes an analysis of the sententia as a prominent and revealing rhetorical device with historically-conditioned social values, a method of investigation he calls a "sociology of rhetoric." He uses prominent examples from Tacitus's account of the reign of Tiberius to set up his sociological approach to ancient rhetoric and goes on to investigate the concept of sententia in the writings of the Greek rhetoricians Anaximenes and Aristotle, the anonymous Roman author of Rhetorica ad Herennium, Cicero, the elder Seneca, and Quintilian, among others. Sinclair argues that criticism of Tacitus's use of sententiae as extraneous to his purposes as a historian is the result of an imperfect understanding of the Greek and Roman tradition of rhetorical historiography in which Tacitus deliberately placed himself. No previous scholar has systematically analyzed the theory behind the use of maxims and epigrams that was developed by the ancient rhetoricians and applied that analysis to a historical work.