In their obsession with internal security, the Roman emperors did not rely on a single unit to act as secret police. In 6 A.D. Augustus (27 B.C.-14 A.D.) had founded the vigiles, a body created to act as Rome's fire brigade: the 7,000-strong unit was militarily organised and also served as night watchmen and secret police. One of the most significant episodes of how the vigiles acted as a security force occurred in 31 A.D., when Tiberius (r. 14-37 A.D.) planned to overthrow the prefect Lucius Aelius Sejanus: not being able to trust the praetorians and the urban cohorts, Tiberius ordered the vigiles to oversee the meeting of the Senate in which the fate of Sejanus was decided. Civilians were also involved in the security operations: freedmen, i.e. slaves who had been freed, were often placed in offices of high responsibility with orders to spy on their subordinates and colleagues, while ordinary citizens - even slaves - were asked, in exchange for a monetary reward, to report on any seditious speech or acts they witnessed. These delatores were so widespread that a climate worthy of 1984, George Orwell's celebrated novel, was palpable in Rome, as described by Philostratus in his Life of Apollonius: ‘To live in a city in which there are so many eyes to see and so many ears to hear that things are and are not, is a serious impediment to anyone who wishes to play at revolution, unless he is completely intent on his own death. On the contrary, it drives prudent and sensible people to walk slowly even when they are engaged in entirely lawful activities.’ Another excerpt from Epictetus points out the dangers of letting your guard down: ‘A soldier, dressed as a civilian, sits by your side and begins to speak ill of Caesar, and then you too, as if you had received from him some assurance of good faith in the fact that he initiated the affront, say in the same way everything you think, and the next thing you know you are led to prison in chains.’