空

It is in that Allegory that he [Plato] sorted out other concepts related to his view of knowing. In the process of coming to know, each person is initially shackled by their senses that constantly deceive them into thinking they know when they do not. They are surrounded by shadows of images of physical things that they take for reality. They are in a cave of darkness and cannot get out of it on their own.

In the world of the senses surrounded by illusions, the Cave, we cannot be said to know anything. We are in darkness. We can actually only make conjectures and have beliefs and opinions about things because those things are shadows of images of physical things. The things we perceive with our senses are actually many steps removed from the physical things that cast the shadows that we see

---(Estep, 2006, p. 99). (Self-Organizing Natural Intelligence)

突然联想到佛教里说的"空”。