Plato's famous "Allegory of the Cave" illustrates the difference between appearance and reality, between truth and falsehood. Plato regards most people as being like the chained prisoners in the cave, who mistake the shadows they see on the walls of the cave for reality.

Most people (i.e. those who aren't enlightened philosophers like Plato) therefore remain in ignorance of what is ultimately true and real. This is a moral as well as a metaphysical question because, according to Plato, it is impossible to live a morally upstanding life while remaining ignorant of the truth.

What's notable here is that, according to Plato, the prisoners in the cave (that is to say, most of humankind) wouldn't want to step outside the confines of the cave even if they were given the opportunity. Even when the philosopher returns to the cave having seen the light, both literally and metaphorically, the other prisoners are reluctant to follow his example. This is because the philosopher, having returned to the cave, would be blind, and the prisoners would infer from this that it would be a bad idea to go outside.

This is clearly a problem for Plato, both from a moral and a metaphysical standpoint. If the vast majority of humankind is content to live in falsehood and ignorance, that's not a good thing. According to Plato's teacher Socrates, the leading of a morally worthwhile life requires knowledge of what is true. Hence, if we don't know what is true, then it is impossible for us to lead a good life.

At the same time, it would appear to indicate that an apprehension of the truth is reserved only for an educated elite, for trained philosophers like Plato and his great mentor Socrates. Only they can realize that the world around us, the world of objects and phenomena, is ultimately just a shadow of what is ultimately real, the world of Forms—unchanging, abstract ideals such as Truth, Beauty, and Goodness.