The cognition of an external object already presupposes the distinction of outside and inside, subject and object, the perceiving and the perceived. When this separation takes place, and is recognized as such, and clung to, the primary nature of the experience is forgotten, and from this endless series of entanglements, intellectual and emotional, takes its rise.
(From the book ‘The Zen Doctrine of No-Mind’ by D.T. Suzuki)
What Daisetz Suzuki points to above, is the cause of our suffering, our living of a life of conflict between here and there. It is the rise of ego that denies the inherent unity of existence. We can experience this unity if we find a way to see things as they truly are, rather than from the viewpoint of ego. How is this done? Well, one method is to just look and see that right now there is no observable separation between this and that, here and there. On a certain fundamental level, you are me and I am you; being open to accepting the facts of the present moment will lead us to actually see this. This is opening the eye of Dharma.