What darkness does marlow see in himself?

Marlow begins to realise many things about himself. I think that one of the larger themes is that he sympathises not with the white colonial oppressors but rather with the black "savages" that are oppressed. Indeed, Marlow begins to see the "white" souls of the black people and the "black" souls of the whites who exploit them; the heart of darkness lies within his own kind. Although Marlow is a product of the 19th century European colonialism, he 

Afederal parliamentary republic is  unlimited.