 Ancient skepticism is, for the most part, a phenomenon of Post-Classical, Hellenistic philosophy. The Academic and Pyrrhonian skeptical movements begin roughly in the third century BCE, and end with Sextus Empiricus in the second century CE. Hellenistic philosophy is a large-scale conversation, not unlike philosophy today. The skeptics (among them Pyrrho, Timon, Arcesilaus, Carneades, Aenesidemus, and Sextus Empiricus) do engage with Pre-Socratic philosophy, Socrates, Protagorean relativism, Plato, and perhaps Aristotle. But their contemporary and principal interlocutors are Epicureans, Stoics, Cynics, and Megarian logicians (cf. Long 2006, ch. 4 and 5).