Tacitus was one of the first to ask whether such powers were given to the head of state because the citizens wanted to give them, or whether they were given for other reasons (for example, because one had a deified ancestor). The latter case led more easily to abuses of power. In Tacitus' opinion, the trend away from a true republic was "irreversible" only when Tiberius established power, shortly after Augustus' death in 14 CE (much later than most historians place the start of the Imperial form of government in Rome). By this time, too many principles defining some powers as "untouchable" had been implemented.