This knowledge is but the assumption we are right... and that is an assumption that we are confident in (as in, we have faith in an assumption). Prove to me that the sky exists, in any more of a way than God exists (God is faith in an assumption). I am an existentialist, if you recall?

Please give me a home where cloud buffalo roam
Where the dear and the strangers can play
Where sometimes is heard a discouraging word
But the skies are not stormy all day