I cannot be sure that the world I take to be natural really is as it appears.   Neither can I be sure that the categorial frame within which I experience it is any kind of absolute.   


In principle this is both an epistemological and political stake in transcendental skepticism.  Reality - not just the world as it appears but my very habits and chemical composition - is ideology. 


Absolute knowledge is knowledge of transcendental skepticism - knowledge of the sheer astonishing power of the world to be otherwise.   But it must be known in an embodied way - believed, loved, yearned for.   Because it is also the sheer power of knowledge to be otherwise.