One of the most forceful stories he told on behalf of the utility of philosophy was what has become known as " The Allegory of the Cave ".  It is perhaps the most famous allegory in philosophy. This was a story that was intended, as he wrote, to compare:
"The effect of education and the lack of it in on our nature ."

At the start of Book 7 of his masterpiece, " The Republic ", Plato tell us about some people living imprisoned in a cave.
They've always lived there and don't know anything about the outside world. There is no natural light in thí cave, the walls are damp and dark. All the inhabitants can see comes from the shadow of things thrown up on the wall by a light of a fire. The cave dwellers get fascinated by these reflections of animals, plants, and people. Moreover, they assume that these shadows are real and that if you pay a lot of attention to them you'll understand and succeed in life. And, they don't, of course, realize that they are looking at mere phantoms. They chat about shadowy things enthusiastically and take great pride in the sophistication and wisdom. Then one day, quite by chance, someone discovers a way out of the cave, out into the open air. At first, it's simply overwhelming. He is dazzled by the brilliant sunshine in which everything is, for the first time, properly illuminated. Gradually his eyes adjust and he encounters the true forms of all those things which he had formerly know only as shadows. He sees actual flowers, the color of birds, the nuances in the bark of trees. He observes stars and grasps the vastness and sublime nature of the universe. As Plato puts it in solemn terms:
" Previously he had been looking merely at phantoms; now he is nearer to the true nature of being "
Out of the compassion, this newly enlightened man decides to leave the sunlit upper world and makes his way back into the cave to try to help out his companions who are still mired in confusion and error. Because he's become used to the bright upper world, he can hardly see anything underground. He stumbles along the damp wet corridors and gets confused. He seems to the others totally unimpressive. When he, in- turn, is unimpressed by them and insists on explaining what the sun is or what a real tree is like. The cave dwellers get sarcastic, then very angry and eventually plot to kill him.

The story of the cave is an allegory of the life of all enlightened people. The cave dwellers are humans before philosophy. The sun is the light of reason. The alienation of the returned philosopher is what all truth tellers can expect when they take their knowledge back to people who have not devoted themselves to thinking. For Plato, we are all for much out of lives in shadow. Many of the things we get excited about, like fame, the perfect partner, a high-status job are infinitely less real than we suppose they are for the most part phantoms projected by our culture onto the walls of out fragile and flawed minds but because everyone around us is insisting that they are genuine we are taken in from a young age. It's not our fault individually.
" No one chooses to be in the cave. That's just where happen to begin, we're all starting from a very difficult place. "