When Vespasian sent for Helvidius Priscus and commanded him not to go into the senate, he replied, "It is in your power not to allow me to be a member of the senate, but so long as I am, I must go in." "Well, go in then," says the emperor, "but say nothing." "Do not ask my opinion, and I will be silent." "But I must ask your opinion." "And I must say what I think right." "But if you do, I shall put you to death." "When then did I tell you that I am immortal? You will do your part, and I will do mine: it is your part to kill; it is mine to die, but not in fear: yours to banish me; mine to depart without sorrow."Epictetus, Discourses, 1.2.19-21
Like his father-in-law, Thrasea Paetus, whose daughter Fannia he had taken as his second wife, he was distinguished for his ardent and courageous republicanism. Although he repeatedly offended his rulers, he held several high offices. During Nero's reign he was quaestor of Achaea and tribune of the plebs (AD 56); he restored peace and order in Armenia, and gained the respect and confidence of the provincials. His declared sympathy with Brutus and Cassius occasioned his banishment in 66.
Having been recalled to Rome by Galba in 68, he at once impeached Eprius Marcellus, the accuser of Thrasea Paetus, but dropped the charge, as the condemnation of Marcellus would have involved a number of senators. As praetor elect he ventured to oppose Vitellius in the senate (Tacitus, Hist. ii. 91), and as praetor (70) he maintained, in opposition to Vespasian, that the management of the finances ought to be left to the discretion of the senate; he proposed that the Temple of Jupiter Best and Greatest, which had been destroyed in the Vitelline/Flavian civil war, should be restored at the public expense; he saluted Vespasian by his private name, and did not recognize him as emperor in his praetorian edicts.
At length he was banished a second time, and shortly afterwards was executed by Vespasian's order. His life, in the form of a warm panegyric, written at his widow's request by Herennius Senecio, caused its author's death in the reign of Domitian.