The truth which Buddhism wishes us to realize is not found on the outside. Why is this so? It is because our human senses are far too limited. They are only for the purpose of species-specific biological adaptation (Darwinian fitness). Vision, for example, is only one octave when in reality there are many higher octaves. Hearing is also limited as with the rest of our human senses. The only place where there is no such sensory limitation is within in the very self (S. pratyâtman).
Within, we have the potential to look beyond the fabric of space/time discovering a proto-field which cannot in anyway be described except to say it is unconditioned—kind of like 'superposition' in Quantum Mechanics. This field, if we can call it that for now, is a very real state which lies beyond the range of our human conceptualizing intellect to disclose. The Buddha taught this realization as a fact. There is an actual attainment. There is also verification—a subject which tends to be overlooked in Buddhism.
Verification assumes that beings all have the Buddha-nature or âtman which is the absolute criterion. Presently, beings are just asleep—they don't yet see the Buddha-nature face to face. It is somewhat like saying we are all rich, we just have to figure out a way to earn wealth. Right now, we are just getting by.
Given that we are this absolute criterion which makes verification possible, it is also a given that nothing chimes with the absolute criterion or the same, Buddha-nature. Everything is more or less unsatisfactory or off kilter for us. We seem to never meet, perfectly, with what perfectly agrees with this criterion.
We never found truth on the outside as mentioned earlier because our senses are inadequate. So we decided to look within, but this doesn't seem to be getting us anywhere either, since we are stuck on the human conceptualizing intellect—it's our makeshift criterion. We can't seem to escape its bewitching power which goes so far as to deceiving us into believing we've realized our Buddha-nature. Try as we might to talk ourselves into it (self-deception) we come away disappointed.