Basically, there are two levels of reality on Earth — individual reality and collective reality.
Your individual reality is yours alone; no other human being has the exact same set of beliefs, and no other human being is perceiving the world from the perspective of your body and its senses.
Collective reality consists of those belief systems that are shared by two or more people.
Collective realities often tend to have more power than individual realities.
Since belief creates our perception of reality, the world of humanity is a reflection of the individual beliefs of every human being, plus the collective beliefs of humankind, presented as a mosaic of composite consciousness (the blending, merging and averaging of the total field of consciousness).
In order for society to function efficiently, human beings enter into various agreements as to which realities will be accepted and which will not.
When enough people agree on a particular reality, it becomes known as a fact.
Everyday facts are real in the sense that the human race has collectively agreed to perceive physical reality in a certain way.
This is obviously necessary in order for humans to live together on this small planet. [...]
The realities with the most power are those that are believed by the most people, or where the belief is the strongest.
Death and taxes seem inevitable because the vast majority of people believe in them.
It is possible for an individual to disagree with death and taxes, but due to the extreme pressure to conform to the mass consciousness, very few individuals have broken out of this collective reality.
Source: Sal Rachele (Life On The Cutting Edge)