Plato's Cave: why most of what we see might be shadow

In The Republic (c. 380 BC), Plato described prisoners chained inside a cave, seeing only shadows of objects projected onto a wall. When one prisoner escapes and sees the real world, the sunlight blinds him; when he returns to tell the others, they mock him. Plato used the allegory to distinguish between the world of appearances (what the senses perceive) and the world of Forms (what reason can grasp). The allegory remains a touchstone for debates about the nature of reality, perception, and the responsibilities of those who 'see more' to share knowledge with others.

Source: Plato, The Republic, Book VII (c. 380 BC)