Presumably as a reaction against the dogmatism of Antiochus, one finds arising in the mid-first century BC the figure of Aenesidemus, originally an Academic, who turns his energies to reviving the scepticism of Pyrrho of Elis. All the four Hellenistic traditions, Platonist, Aristotelian, Stoic and Epicurean, continued vigorous throughout the period, though, interestingly, without any formal school structure to support them. Apart from the Epicureans, then, there is no clear evidence of a continuous, centralized structure for any of the major schools throughout the period. On the other hand, this lack of a central authority did not prevent the development of a considerable degree of systematization of doctrine. In this the Platonists and the Peripatetics were doubtless influenced by the scholastic tendencies of the Stoic school. It seems suitable, in a contribution to a general history, to close with some remarks as to the role or roles assumed by philosophers in society, as these were varied and important.