Everyone should have dreamed, but can you really tell the difference between dreams and reality?
Suppose A is reality, B is the first-level dream, C is the second-level dream within a dream, and D is the third-level dream.
In D, you cannot prove whether you are in a dream, you can only realize that it may be a dream. Only when you wake up from dream D, you can be sure that D is a dream. When you wake up from C to B, and from B to A. You can know that DCB is all a dream, but is A really a reality?
Well, actually I just had an n-level dream and was a little confused.
Intention: Truth is also like illusion, seek truth in illusion.