What you perceive to be the truth may not necessarily be the truth. Just as one object can give rise to multiple percepts.

The processes of perception routinely alter what humans see. When people view something with a preconceived concept about it, they tend to take those concept and see them whether or not they are there. This problem stems from the fact that humans are unable to understand new information, without the inherent bias of their previous knowledge. A person’s knowledge creates his or her reality as much as the truth, because the human mind can only contemplate that to which it has been exposed. When objects are viewed without understanding, the mind will try to reach for something that it already recognizes, in order to process what it is viewing. That which most closely relates to the unfamiliar from our past experiences, makes up what we see when we look at things that we don’t comprehend.

Interesting wall of text.

P.S Source from wikipedia (:

Here's another vid from the dood who made the above vid