they're saying your world is illusion.
I believe this is caused by where one focus's.
Let me try and explain and use Craig as an example.
Craig is a big guy and generally slow moving, so to focus on that I could think he is 'slow'
However, to talk with him shows he is quick and deep thinking, which offers up two new possibilities, he is quick, or he is deep.
So where I focus will determine my perception of Craig, but none of the points of focus will actually BE Craig, he is a combination of things that can only be seen with a broader view, so, to me, this proves that a narrow focus will give a false perception.
Open this up into a view of life, death or anything else and it makes the 'real' easier to see, at least, it does to me.
Posted with thanks to Craig for being an example to us all