On What Is - Classic Text | Alexandria
On What Is (Περὶ τοῦ ὄντος/Peri tou ontos), also known as "On Nature," is Parmenides' sole surviving work, a philosophical poem composed in hexameter verse around 475 BCE that fundamentally shaped Western metaphysical thought. Written in the tradition of didactic epic poetry, this enigmatic text presents its teachings through an allegorical journey where a young man is guided by an unnamed goddess who reveals the nature of reality and truth.
The work first emerges in the historical record through references by Plato and Aristotle, though the complete text has been lost to time. Only about 160 lines of the original poem survive, primarily preserved through quotations by later philosophers and commentators. The poem emerged during a pivotal period in ancient Greek thought, as pre-Socratic philosophers were beginning to question fundamental aspects of reality and human knowledge, marking a transition from mythological to rational explanations of existence.
The poem consists of three main sections: a proem (introduction) describing the narrator's journey to the goddess, followed by "The Way of Truth" and "The Way of Opinion." Parmenides' radical proposition that reality is single, unchanging, and eternal—that what "is" cannot "not be"—established the foundation for logical reasoning and influenced philosophical thought from Plato through modern times. His strict logical arguments about the nature of being introduced formal deductive reasoning to Western philosophy, earning him recognition as the "father of metaphysics."
The text's influence extends beyond philosophy into modern physics and cosmology, where Parmenidean concepts of unchanging reality beneath apparent change echo in theories of conservation laws and spacetime. Contemporary scholars continue to debate the precise meaning of Parmenides' cryptic verses, particularly the relationship between his absolute conception of being and our everyday experience of change and multiplicity. This tension between apparent reality and underlying truth remains relevant to current discussions in physics, philosophy of mind, and epistemology, making "On What Is" a living document that continues to challenge and inspire thinkers across disciplines. The enduring mystery of Parmenides' full meaning raises a provocative question: How can ancient wisdom about the nature of reality inform our understanding of contemporary scientific discoveries?