Being and non-being
In his poem On Nature, a goddess declares that thinking and being are the same — whatever can be thought must exist. That claim opened all of ontology after it.
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Parmenides
Founder of the Eleatics, father of "Being"
Those Who Ground an Idea Into a Whole System · Disciples & School-Builders
OntologyMonismReason
Who they are
Parmenides (c. 515–450 BC), heart of the Eleatic school, argued that "what is, is; what is not, is not": reality is one, eternal, unchanging and indivisible, while change and plurality are illusions of the senses. He first set reason above sense-experience and founded Western metaphysics.
Primary sourcesFragments of the poem On NaturePlato, Parmenides
Key stories
Relationships
Disciple
Echoes today
Below are how modern works borrow or reinterpret this name or story — not the original material. The two differ, so keep them apart.
OntologyAll later discussion of "being" as a philosophical theme traces back to him.