Exercising opposition to an established government is part of the political game and democratic systems assume it as something normal. But where power is absolute, things become more difficult and the problem is that, throughout history, this has been the general trend. That is why it is surprising to discover that in a regime as autocratic as that of the Roman Empire, where the functions of the Senate were relegated, there was a peculiar opposition movement during the 1st century AD. starring philosophers:the so-called stoic opposition .
Stoicism was a philosophical current, founded by the Greek Zeno of Citium three centuries before Christ, which focused its attention on Man from a materialistic and, above all, moralistic perspective. Related to cynicism, he considers that the highest good is happiness and that it consists of virtue which, in turn, is based on the concept vivere secundundum naturam (live according to nature). It refers to human nature, rational, accepting destiny and adapting to it.
All this implies getting rid of the passions to achieve ataraxia (apathy, imperturbability), which provides happiness to isolate oneself from outbursts and pains, for which it is necessary to reduce personal needs:sustine et abstine (support and renounce). Thus, the Man, the wise man, manages to be independent, is not subject to duties and his reason merges with nature, reaching virtue and through it happiness. The term Stoicism derives from the place where Zeno gave his teachings, the stoà poiliké of Athens, although the doctrine, coinciding with the Hellenistic period, lasted approximately half a millennium, until the II AD
During that time, which is usually divided into three stages (old, middle and new), some figures emerged such as Cleanthes of Asos, Chrysippus, Panecio of Rhodes, Posidonius... If the second was the one who structured the teachings in writing, the third was the one who introduced the doctrine in Rome (he was a friend of Scipio) and the fourth served as Cicero's teacher. The last period, almost exclusively Roman, had Seneca, Nero's teacher, as its main protagonist, followed by others such as the freedman Epictetus or the emperor Marcus Aurelius.
However, unlike the Cynics and Epicureans, the Stoics retained an interest in public life, in social relations, basing themselves on human nature. Considering that it is universal, they despised the polis, the city, in favor of a cosmopolitanism that made men equal citizens of the world. All this can serve as a clue to understand why the Stoic opposition was politically against the Roman emperors or, at least, against some of them such as Nero, Vespasian and Domitian.
In reality, there is no unanimity among historians when it comes to agreeing whether it was an organized movement from a philosophical perspective or it was all due to a socio-political reaction, since a good part of those philosophers belonged to the senatorial class, deprived of their rights. privileges and prerogatives by the absolute imperial power; In addition, there were reprisals completely unrelated to Stoicism and the preserved texts of that doctrine do not pay special attention to politics. In fact, the term stoic opposition it is late; It was coined by the French historian and philologist Gaston Boissier in the 19th century.
But it is admitted that there was a certain ethical link and there is no doubt that Stocism was under suspicion in the second half of the 1st century AD, its representatives being exiled from Rome. It was the culmination of a process that began in the previous century, when Cato of Utica (great-grandson of Cato the Elder ), who during his tribunate had had clashes with Julius Caesar by accusing him of being part of the Catilina conspiracy and then supported Pompey in the civil war, committed suicide considering himself incapable of living under the tyranny that his enemy was going to impose .
Cato was stoic and became a role model for all. Seneca, who also professed that philosophy, compared his tragic end to that of Socrates in a context in which a genuine anti-Stoic persecution was about to break out. But the real harassment began in Nero's time with Rubelius Plautus, a consular senator from the Julio-Claudian dynasty who was accused by the emperor of sedition and intrigue and was expelled to Asia Minor. He finally ended up killed.
Then the old Barea Sorano, who was his friend (and a follower of Stoicism, like him), was sentenced to death along with his daughter Servilia, who was accused of sorcery; they were given the classic way out of honorable suicide. Soranus had been denounced by his teacher, Publius Egnatio Celer, who received a reward for it... until he was later denounced in turn by Musonius Rufus, a Stoic teacher who played a decisive role in that mess, as we shall see. 
Around 65 AD, Seneca himself (who had been the emperor's tutor) and his nephew Lucanus were forced to take their own lives when they were accused of participating in the conspiracy of Gaius Calpurnius Piso. The following year, a senator who was a disciple of Rufo named Trasea Peto promoted a campaign of abstentionism in political life that included not swearing allegiance to the emperor, not making sacrifices for him, etc. Failure to attend Poppea's funeral and the tares planted by another senator, Cossutiano Capito, earned him the death penalty. Two of his friends, also Stoics, Paconio Agripino and Helvidius Priscus, were exiled in the same trial.
Thus came the mandate of Vespasian, who continued the anti-stoic policy on the advice of the aforementioned Musonius Rufo. Paradoxically, he was a friend of Rubelio Plautus and had gone into exile with him but was allowed to return... to be banished again for participating -falsely, apparently- in the aforementioned Piso conspiracy. However, he was also able to return, he became the teacher of Epictetus and, according to Dio Cassius, he was the one who convinced Vespasian of the convenience of expelling the Stoics from Rome, because they were arrogant and arrogant. The emperor would listen to him in the year 71 but four later he also expelled Rufo (by the way, he would manage to return a third time when the emperor died). 
As is known, Vespasian was thoroughly used against the Senate and for this reason, despite the fact that he expelled most of the Stoics from Rome, he still had to see how a new opponent arose in the figure of Helvidio Priscus. He was the son-in-law of Trasea Peto and defender of senatorial competence to deal with economic affairs, which openly confronted the imperial authority; something aggravated by the fact that, as praetor, in his edicts he always named Vespasian by his name without alluding to his status as emperor. Consequently, he was banished first and executed afterwards.
Vespasian's heirs were his sons Titus and Domitian successively. During the mandate of the latter, the persecution of opponents intensified. The list begins with the son of Helvidio Prisco, author of a satirical work on Paris and Oenone that was interpreted as a mockery of the marriage between the emperor and Domicia Longina, since it was known that she had a lover named Paris; when made public, Prisco lost his life and she was disowned. The wave of blood continued with the senator and ex-consul Aruleno Rústico, eliminated after writing a praise for his friend Trasea Peto, exactly as happened with Herenio Senecio, who published a eulogy for Helvidio Prisco commissioned by his widow, Fannia, who She was also the daughter of Trasea Peto (she came out better off, only with exile).
Fed up with the Stoics, Domitian expelled them not only from the capital but from the entire Italian peninsula. Among the most distinguished victims were Dion Crisóstomo, disciple of the ineffable Musonio Rufo and grandfather of Dión Casio, who was able to return when his friend Nerva rose to power; also Epictetus, ex-slave of Nero's secretary and ardent defender of Priscus, whom he set as an example of conduct for his students. Epictetus went to Greece and opened a school of philosophy in Nicopolis, becoming a reference for Stoicism.
Probably he and all the other victims of reprisals would smile if they had known that, shortly after, the adoptive son of Antoninus Pius, Marcus Aurelius, who had received Stoic training from teachers like Junius Rusticus (descendant of that Arulene Rusticus struck down by Vespasian), did not not only ascend to the imperial throne but in his Meditations he would call Nero a tyrant and would thank his tutors for the teachings on virtuous characters such as Trasea Peto or Helvidio Prisco.