
Mysticism is described in many ways, some of which are related to nature, others of which are related to religion or God. Frederick Streng provides a particularly accurate definition: An interior illumination of reality that results in ultimate freedom. Some say it's a way of seeing reality 'objectively.' Even more profound, is the evidence supporting the validity of mystical experiences. They are very real.
We accept, that the mystical experience happens, and that it affects the whole man: if it affected only the non-empirical part (the spirit, or soul) then the mystic would have no memory of it, for memory depends on neuronal pathways in the physical brain, and he could give no account whatever of it; he would not even be aware that it had happened. This is beautiful to me because I am a firm believer that materialism is bullshit. Pardon my French, but it just seems really ignorant to deny the relationship between your body and your mind. They are two separate entities, yes, but they are connected by some non-physical phenomenon. We could not recall memories of mystical experiences if they weren't somehow connected physically to us.
Science proved that memory depends on neuronal pathways, thus it proves that an altered state of consciousness (I prefer the term transcendental because the word altered leads to the unfortunate notion that all other states are deviations from the ordinary waking state) isn't any less real than 'reality.' A personal experience is just as, if not more, real than a communal one. Just because other people can't see or comprehend what is happening inside your own body and mind doesn't make it any less real. It means you are the controller of your own reality.
Obviously, the only evidence we have (that we can share with others about our experiences) is our memories. And in the case that 'seeing is believing,' others may find the validity of your shared experience inadequate. It is unfortunate, but at the same time those who can't open their minds are blind to mysticism anyway. Thus, they don't posses that frame of reference. To truly understand, one must experience. And of course all of our experiences are quite different from each other.
To sum it up, mystical consciousness is in fact, very real. Your private experiences, or qualia, are just as real as the 'reality' that others around you perceive. Take that journey through time and space whenever you can. The mind is a beautiful thing. It's a miracle.