Even without the obstruction of a wall, I would not be able to see the tree from a distance. Distance obliterates vision with the result that the otherwise visible world becomes invisible. What we can see with the help of the microscope, we cannot see with bare eyes. We can see only the gross material world. The eyes are also gross.
Reality is subtle.
So it can be grasped with only the intuitional vision that is developed after the karma particles eclipsing consciousness have been removed. Consciousness is formless. We cannot see it as we see the tree. There may be an obstruction between us and the tree, or the tree may be at a distance from us, but consciousness is neither hidden nor at a distance from me. The ego is the manifestation of consciousness and a bridge between it and the world.