There can be nothing less obscure than the Self; after all, the Self is the seer, the experiencer, of all phenomena. By virtue of the fact that one 'inhabits' the Self, it is more concrete, in a sense, than the material world.
Mysticism is not occultism or parapsychology, it is simply the realisation of the advaita (non-dual) state.
The eye with which I see God
is the same with which God sees me.
My eye and God’s eye is one
and one sight, and one knowledge,
and one love.
- Meister Eckhart (medieval Christian