Plato, philosopher in classical Greece, his teacher, Socrates, and his most famous student, Aristotle. Plato describes the state of unenlightened man in the well known allegory, Plato's Allegory of the Cave.
In the allegory, Plato likens people untutored in the Theory of Forms to prisoners chained in a cave, unable to turn their heads. All they can see is the wall of the cave. Behind them burns a fire. Between the fire and the prisoners there is a parapet, along which puppeteers can walk. The puppeteers, who are behind the prisoners, hold up puppets that cast shadows on the wall of the cave. The prisoners are unable to see these puppets or the real objects that pass behind them.
What the prisoners see and hear are shadows and echoes cast by objects that they do not see.
Such prisoners would mistakenly assume the appearances before them for reality. They would think the things they see on the wall (the shadows) were real; they would know nothing of the real causes of the shadows.
If a prisoner says “That's a book” he thinks that the word “book” refers to the very thing he is looking at. But he would be incorrect. He is only looking at a shadow. The real referent of the word “book” he cannot see. To see it, he would have to turn his head around.
Plato’s point: the general terms of our language are not “names” of the physical objects that we can see. They are actually names of things that we cannot see, things that we can only grasp with the mind. The captives would then award one from another to whom could guess the next shadow to appear or the measurement and meanings of the shadows and resign those that were not interested in their little game.
Then imagine some former captives escaped and returned to smite the captures by releasing a prisoner, when the prisoner is released, he will turn his head and see the situation regarding his perception of reality. Then he will realize the error and all the logic for understanding their world was now completely meaningless, except for the captives that remained untied they carried on as before. (He would want to return to captivity and scold those that released him, knowing that lofty thoughts and ideas are not fundamental to the situation of existence)