Vespasian, having secured power, tried to enforce a dynastic policy, while the opposition in the Senate and the republican thinkers of the age, influenced by Stoic ideas, stood up against the hereditary rule. Helvidius Priscus, the leader of the opposition, and Thrasea Paetus, his father-in-law, became emblematic figures of these decades, and their names were associated with the cult of Brutus and Catos. Pliny the Elder, a republican in theory, but still loyal to Vespasian, did not express his ideas openly in the question of hereditary rule. However, we can reconstruct his critical attitude from his Stoic ideals and from a remark concerning the election of kings in Taprobane, an assertion otherwise not confirmed by Oriental sources. Pliny's statement might have supported the opposition inside the Senate in the fight for the restriction of imperial autocracy, which finally resulted in the enforcement of the concept of 'adoptio'.