While physical things are never completely known but only through a sheaf of adumbrations, things in the mind, that is thoughts, are entirely self-revealing. For mental objects being and appearance are not two. This understanding does not hold up under closer scrutiny, if he distinction (the very definition of the mind) seems obvious this is only because it is tacitly presumed. If a mental objects exist it is only a relative existence, like something you are quite sure of in a dream but when you wake up is revealed to be an interpretation woven around something completely different. Anything you think you have before you is only what it appears to be relative to the world that has been imagined around it. Here it is not the object that is known via adumbrations but the knower, or the putative knowledge. If there is something that it 'really is' that would be what, without changing itself, gives rise to every different thing you think it is in every possible form of consciousness that reveals it. Only in that way could it have complete self-identity without any distinction of knower and known.