A Question of Existence
Reality...or the understanding of our inability to truly understand it, has been my pet "area of study" for quite some time now. Within Wicca and Druidry you reach a point of practice. You have learnt the how, now enjoy the "do". Admittedly, the mysteries are something that are forever cropping up, as each cycle passes more things are revealed - this is how we expand our spiritual understanding. It is part of how we spiritually grow. The atmosphere of study, though, cannot be perpetual.
Personally, for me, the study and understanding of reality is the only true "religion" upon which we build many other sub-systems which we all mistakenly call religion. Upon a Wiccan altar do we call an athame a religion? Or the altar itself? Of course not, it is merely a sub-section of a practice. Wicca is a practice. Druidry is a practice. Christianity is a practice. What are we practicing? We are attempting to understand the universe, but because our human faculties are too limited to do so we resort to metaphysical "boundary-lifting" methods to try and understand it. These are a great way of going about things, and for many a means of feeling content with the understanding it gives.
I'm a Gemini, I can't help it - I need to look further.
A first step in looking at reality can be taken by contemplating the following statement...
"(1) since the one sure thing we can say about fundamental matter is that it is vibrating and, (2) since all vibrations are theoretically sound, then (3) it is not unreasonable to suggest that the universe is music and should be perceived as such."
So, is reality "sound", a sequence of vibrational states that causes a "existence"?
Well, it's certainly a possibility.
There is also the issues of light. If someone told you that something you hold to be firmly real is just a figment of your imagination, that it does not exist outside of your head, you would probably say "hey, I would like to politely request you put a sock in it!", hell people in psychiatric care are told this at almost every session they have, I know I am.
Rainbows. They are not real and are purely an "idea" in your mind. A reaction to an external stimuli that does not exist itself outside your mind. Time to crack out the psychotropics? Not at all.
When you see a rainbow in the sky, all you are seeing is a reaction in your brain to light having passed through water. It is purely reactionary - every rainbow looks different to everyone else. There are a profuse amount of animals who simply cannot see rainbows. Those who are colourblind and those whose brains interpret light differently.
To add a quote from wikipedia to help clarify
"A rainbow does not actually exist at a particular location in the sky. It is an optical illusion whose apparent position depends on the observer's location and the position of the sun. All raindrops refract and reflect the sunlight in the same way, but only the light from some raindrops reaches the observer's eye. This light is what constitutes the rainbow for that observer."
The rainbow does not exist outside us - yet we can see it, we can perceive it, we can agree it is there. How does this factor into the supposed and popular way reality works. Well, of course, it doesn't. Spend some time, think on it. Take a look around you, I mean really look.