In Plato's "Allegory of the Cave", people are watching shadow forms cast on the wall, thinking that they are seeing the real world. In the movie, "The Matrix", most are also living in a false reality. Simulation Theory is very popular now, and it makes for an interesting thought exercise. How would you live your life differently if you found out that we are actually living in a computer simulation (or dream world)? The philosopher Rene Descartes, who is famous for the quote "I think, therefore I AM", gave it a lot of thought and came to the conclusion that, as long as he was thinking or feeling, he did indeed exist - even if the world was an illusion. Food for thought.