Consciousness is the only thing in your world, the world, that is unsubstitutable. It doesn't seem this way, it seems as if just the opposite is the case, as if there are so many unique and special objects and experiences and as if someone else might as well and usually does encounter or enjoy or suffer them. The unsubstitutability of consciousness hides from view, it has no fanfare, all of its uniqueness is transferred out to external and public matters, it is in a way the most banal thing in the world. The real transcendental illusion is this inversion of values, the worldly world feeds on it, it is the object of desire. The thought experiment cognate to vedantic subtraction is simply to ask whether such and such could be replaced by a more or less perfect simulation and then to find the one 'thing', the only one which cannot.