 Parmenides, born ca. 510 BCE in the Greek colony of Elea in southern Italy (south of Naples, and now known as Velia), explores the nature of philosophical inquiry, concentrating less on the contents of knowledge or understanding (although he has views about these) than on what sort of thing can be understood. Xenophanes identified genuine knowledge with the grasping of the sure and certain truth and claimed that “no man has seen” it, at least with respect to some topics (DK21B34/LM8D49); Heraclitus had asserted that divine nature, not human, has right understanding (DK22B78/LM9D74), although he implies that some humans can acquire divine-like understanding. Parmenides argues that human thought can reach genuine knowledge or understanding, and that there are certain marks or signs that act as guarantees that the goal of knowledge has been reached. A fundamental part of Parmenides’ claim is that what must be (cannot not-be, as Parmenides puts it) is more knowable than what is merely contingent (what may or may not be), which can be the object only of belief. 