From Google I find that this is a line from a poem by Edgar Allan Poe, http://www.poetryfoundation.org/poem/237388 , "A Dream Within A Dream." It is very poetic language and I'm not sure I understand it. As another poet, Archibald MacLeish said, "A poem should not mean, but be.", "A dream within a dream" refers to something that has literally happened to me. Has it happened to you? In my dream, I dream that I have fallen asleep and am dreaming. I then dream that I have woken up--into the first dream. When I finally wake up, naturally, it makes me wonder: "HAVE I really woken up this time? Or have I just emerged into another dream? How many dreams-within-dreams are there?" Perceptual psychology teaches us that the seemingly stable "real world" we live in is, in fact, a sort of elaborate illusion constructed with a lot of work by the brain. Philosophers have long debated on how we know what is real and what is imagined. Chuang Chou wrote "Now I do not know whether I was then a man dreaming I was a butterfly, or whether I am now a butterfly, dreaming I am a man."

Alternatively, neither is it true that matter is all that exists. Abstract conceptions exist, as is shown in Mathematics.

It means that everything is an illusion. It is an absurd conclusion, that has some popularity with modern people. If anyone things a solid wall is a dream, they should bend their head down and run into it. I think the evidence will show that the wall is not a dream.

distinguish between reality and fantasy, asking, "Is all that we see or seem but a dream within a dream?" that's it.... :)

distinguish between reality and fantasy, asking, "Is all that we see or seem but a dream within a dream?" that's it.... :)