In a way, I'd regard it as a justifiable position to contend that all "reality" is mediated; according to much current research, consciousness itself is merely - though I would hardly describe it as "mere" - an artefact of cerebral process, a kind of luxurious epiphenomenon, a happy accident of having a sufficiently complex brain. Consciousness apart, everything I experience is mediated through one sense or another, those senses being themselves tangled up in consciousness. I'd not go so far as to say that everything mediated by the senses is necessarily falsified by them, though psychology has shown time and again that the senses can be fooled by, often, exceedingly simple experiments that show up defects in the sensory process.
That given, I'll hold that sensory data is provisional. That's one of my favourite words, I admit. Provisional in that absolute certainty isn't accessible either in or through it. Then is consciousness a source of certainty? Certainly not: dreams, delusions, hallucinations - we have a rich vocabulary for handling phenomena of consciousness which are evidently not correlated with (suppositional) reality. Then where lies a reality of certainty? not in the senses, and not in the inner self. If there is one, I hold it to be necessarily inaccessible.
It follows, then, that if enlightenment is only available from the contemplation of "reality", it is itself inaccessible, despite prayers, fasting, rituals, observances, or whatever.