3 "is a unique number" (as Ancient Aliens would state it) because it is representative of 'perspective' reality (or the reality of perspectives?). Many philosophies and religions are laid out as a battle between good and evil. Some very astute religions (philosophies? where is the line drawn?!?) have taken this a step further as chaos vs. order.
"But what does this have to do with the number 3?!" you may ask.
Of course, 3 is everything! In the religious battles of good vs. evil there is always a 3rd side to the story: mankind. Or in the case of chaos vs. order the middle is "the dao" (or "the way").
Both of these ideas are so close to truth. When it's good vs. evil the neutral zone is mankind, or who we are. When it's chaos vs. order the neutral zone is "the way," or what we do.
In reality it is everything vs. nothing and the neutral zone is perspective, or consciousness. In essence, consciousness is the phenomenon that occurs at the interface of two extremes. It is the existence that we all experience. It is untouchable because when it is breached on either side it is no longer an interface of contrast. In other words, consciousness is awareness, not knowledge. In order to truly understand something you must be separate from it -- this is the fractional nature of our reality.
Untouchable and unknowable at the same time and us, right in the middle.