Oblivion of being - not that what you experience is an illusion but that the apparent experiencer is. What is doubtful in experience is just who or what it is that it opens to, or open from. This is a question you can ask yourself but it yields no answer, not because you are mired is unwieldy concepts designed for the manipulation of objects in space and time but because attention won't bend around far enough - it gets ahead of itself and seizes on something extraneous, it goes back to some subtle object, a fringe of thought. That's why there is talk of something like waking up from a dream - the images don't change but the dreamer is replaced by another who was there all along but unknown. It is always possible to discover yourself to be another kind of subject because the subject position is never filled out in the picture - there's nothing you can see there, it's guesswork anchored in whatever sensations seem the most reliable at the time. That's where the free-play is, the undiscovered degrees of freedom - and like waking from a dream whatever succeeds the ordinary oblivion is felt to be the most natural thing in the world, is instantly recognised as what you were all along - and there is no limit to how far this can go - self after self, and principle of selfness after all selves.