Crazy how we separate the idea of knowing from what is known... we invented that distinction! We split Awareness, our universe of experience, without even realising-- the world and me as two, two who are never going to get on!
That tree - did it fall if no-one saw it? Depends whether you're asking from a theoretical view of the world, or from direct conscious experience!
Check your understanding of basic Buddhism, with these deft definitions... e.g. RETREAT - advance...
Does sound travel from an object to the self which hears it? Is that our experience - or our theory? Does it matter?
I am sitting here. Is that statement true? Your answer will be useless, unless...
Is it a "thing" only because we think it is? Is thing-ness a thought? Then what is reality?
Insight is meditation doing itself! Can this be true?
If it's only a thought that there is an "I", are we nothing but a causal process?
Has thinking got you in an arm-lock? Break free, check The Four Noble Truths of Thinking... [click on the title above]
Where is the 'me' that's the same person as when I was a baby?
Pieces of Five 