It seems to me that I have found – in a dreamlike state by the way – the one thing that lets us know dreamland from reality. Dreamland has several qualities that apparently characterize it unequivocally: absurdity, impossibility, profundity of meaning in inexistent words, extreme intensity of feelings and many more, which make dreams dreamlike. But these are neither sufficient nor necessary, some of them can be qualities of reality too and make it feel just as dreamlike.
Consciousness, it would seem, doesn’t seem to care too much about the plausibility of the context it operates in; we mostly don’t realize that we are in a dream because something is weird or unusual, we just go along with that. In fact there are not as many surprises in dreamland – in spite of how much more unexpected things are there – as in reality.
But there is one definitive difference between reality and dreamland: the latter is wholly esoteric to the mind. Reality is perceived through the senses before consciousness experiences it, but the world of dreams has to be made up on the go by the same mind that is going to experience it immediately afterwards. Now, do you know that little inner voice that comments on the world just as we are taking it in? That same little voice also comments on dreamland as it is being made up, but it goes on in a different tone. Instead of checking against memory and known fact, it checks the quality of what is coming up.
And that is the one subtle thing that we can know dreams by, the difference of tone. We don’t need the fictional oneironaut’s spinning top, all we need to do is listen to our inner voice as it chatters about what we are in the midst of.