 In the literature of the Republic, and on all formal occasions, such as when a senator was called upon to speak, it was customary to address a citizen by praenomen and nomen; or, if this were insufficient to distinguish him from other members of the gens, by praenomen and cognomen.In imperial times, the praenomen became increasingly confused by the practices of the aristocracy.The emperors usually prefixed "Imperator" to their names as a praenomen, while at the same time retaining their own praenomina; but because most of the early emperors were legally adopted by their predecessors, and formally assumed new names, even these were subject to change.