Reality or is it?

Yet another striker from an one of the usual time-pass items of mine, anime, Naruto Shippuden, in this case. Explaining the scenario of this phrase could be a complication, so I will just put the phrase down, as the relevance with the scene is not required to understand the same.

"In-order to survive, we cling to all we know and understand, labeling them as reality. But knowledge and understanding are ambiguous. That reality could be an illusion. And we end up living in assumptions."