The concept of Being runs throughout the history of philosophy, from its very beginnings. Although already present in Indian philosophy since the 9th century BC, it was the Eleatic Parmenides who introduced this long debate to the West, a debate that has spanned centuries and diverse cultures to the present day.

Being is therefore one of the fundamental concepts of the Western philosophical tradition. Usually, in the Greek tradition, the word BEING (einai) assumes four different meanings, which Plato will present in more detail in the Sophist dialogue, thus solving the logical and semantic problems underlying some of the central formulations of the Republic.

1. Existence: to express the fact that a certain thing exists. For example: "the grass is" (= exists), but also "the unicorn is" (at least in the sense of mental existence). Let us remember that the Greeks did not have a specific word for existence.
2. Identity: to identify and/or distinguish something and/or someone in relation to oneself and/or others. For example, "A=A" or "Beauty is beautiful".
3. Predication: to express a property of a given object. For example: "y is x" or the apple is red. Plato discovered that a condition of predication is "there must be no identity between the referents of the names placed in the positions of subject and predicate." For example: "Venus is the morning star." Grammatically, we have a subject and a predicate, but logically we have a false predication, since "Venus" and "the morning star" are terms whose object is the same, one of the planets in the Solar System.
4. Veritative: In his later dialogues, Plato managed to separate veritative values ​​from ontology; that is, true and false became qualities of discourse about the world. Plato shifts truth from BEING to discourse. The metalinguistic sense of truth allows the verb TO BE to signify the truth of a proposition. In philosophy, being is considered not only as a verb (to exist) but also as a noun ("everything that is").

The terms "being" and "existence" can have different meanings, although in everyday language they may be synonymous ("being" as in "the fact of being" = existence). The identitative and predicative forms are the subject of study in logic.