In 57, the year after his consulship, Thrasea supported the cause of the
Cilicians accusing their late governor,
Cossutianus Capito, of
extortion, and the prosecution succeeded apparently largely through his influence. But Tacitus' first reference to him in the
Annals relates to the following year, when he surprised both friends and enemies by speaking against a routine motion in the senate, a request by the Syracusans to exceed the statutory number of gladiators at their games. The objections to this which Tacitus attributes to (anonymous) "detractors" show, if accurate, that Thrasea already had a reputation for opposition to the status quo and for dedication to the ideal of senatorial freedom. To his friends, Thrasea explained that he was not unaware of the real state of affairs, but gave the senate the credit of understanding that those who paid attention to trivial matters would not pass over more important ones—leaving unspoken some such phrase as "if they were permitted real debate on such issues". In spring of the following year, he first openly showed his disgust at the behaviour of Nero and the obsequiousness of the senate after the emperor's letter justifying the murder of
Agrippina had been read and various motions congratulating Nero proposed. Senatorial procedure required each individual in turn to give his opinion on the motion, and Thrasea chose to walk out of the meeting since, according to Dio, "he could not say what he would and would not say what he could". His withdrawal from the Neronian political scene continued with his policy of absenteeism continuing later that year as he refused at the
Juvenalia to applaud Nero's singing. In 62, the
praetor Antistius Sosianus, who had written abusive poems about Nero, was accused on a
maiestas charge by Thrasea's old enemy
Cossutianus Capito, who had recently been restored to the senate through the influence of his father-in-law
Tigellinus. Thrasea dissented from the proposal to impose the death sentence and argued that the proper legal penalty for such an offence was exile. His view won majority assent, and was eventually passed, despite a clearly unfavourable response from Nero, whom the consuls had consulted when the vote was taken. Tacitus' narrative in this section shows Thrasea attempting to claw back to the senate one of the cornerstone virtues of imperial propaganda and ideology, the of the emperor, while also setting a precedent against death sentences for such offences. Parallels have also been seen with Caesar's speech in the Sallust's Catilinarian monograph and Tacitus' narrative of
Marcus Lepidus' defence of a poet during the reign of Tiberius. In the same year, at the trial of the Cretan Claudius Timarchus in the senate, the defendant was alleged to have said several times that it was in his power whether the
proconsul of Crete received the thanks of the province or not. Thrasea proposed that such abuses should be prevented by the prohibition of such votes of thanks. Once again he carried the majority, but a
senatus consultum was not passed until the consuls had ascertained the views of the emperor. The following year made plain Nero's displeasure with Thrasea. When a daughter was born to the emperor at
Antium, the senate went in a body to offer congratulations, but Thrasea was expressly excluded by Nero. Such 'renunciations of friendship' on the part of the emperor were normally the prelude to the victim's death, but unexpectedly Nero seems to have changed his mind at this point, perhaps due to fluctuating power dynamics with Tigellinus, who as Capito's father-in-law might be presumed to have a strong motive to wish for Thrasea's elimination. It was said that when Nero told Seneca he had been reconciled with Thrasea, Seneca congratulated him on recovering a valuable friendship, rather than praising him for his clemency. From about this time, however, Thrasea withdrew from political life. We do not know exactly when he took this decision (Tacitus makes Capito say in 66 that 'for three years he has not entered the senate-house' but Capito's list of complaints against him is clearly contentious and possibly unreliable), nor what was the catalyst for such a volte-face, but it was clear that it was intended, and understood, as itself a political action, especially coming from one who had previously applied himself so assiduously to senatorial business; it was the ultimate form of protest. During this time, Thrasea continued to look after the interests of his clients. It was probably also in this period that he wrote his Life of
Cato, in which he praised the advocate of senatorial freedom against
Caesar, with whom he also shared an interest in Stoicism. This work, now lost, was a major source for
Plutarch's life of the younger Cato. == Trial and death ==