Definition
The most fundamental concept in philosophy, referring to existence itself or the nature of what exists.
Explanation
Being has been a central concern of philosophy since the ancient Greeks. Parmenides argued that Being is one, unchanging, and eternal. Aristotle developed the study of 'being qua being' as the subject of metaphysics. In modern philosophy, Heidegger made the 'question of Being' central to his entire philosophical project.