The "Matrix" and the "World was a Dream" allegories make more transparent an ultimate, cold, hard truth: leave aside the parallels, for even if this was to be the one sole reality, you still can be disconnected from it without ever realizing. Think about it and you will immediately remember of people and of your own experiences as examples. How many times have you found yourself in disbelief of how could you have been so absorbed in a vision that resulted to be false?