"What is distinguishable is not necessarily separable." (1)
Just because you see an eddy in a stream it doesn't mean that an eddy is separate from the stream.
"The imaginary line separating objectivity and subjectivity, reality and illusion, facts and theory, is literally imaginable." (2)
Just because you can imagine a (causal) line between any two points (or any two events) it doesn't necessarily mean that a line (of connection between these two points) actually exists. First mind creates dots/data-points (that aren't there) and then mind connects these dots/data-points into a line that wasn't there. And the imaginable - suddenly - becomes real.
Ponder: if an illusion (of self) exists is it still an illusion?
1, 2 Meditations through Rg Veda (Antonio de Nicolas)