Full Idea
A central aim of German Idealism is to overcome Kant's oppositions between appearances and thing in themselves, and between receptivity and spontaneity.
Clarification
'Spontaneity' refers to our imposing categories on experiences
Gist of Idea
German Idealism tried to stop oppositions of appearances/things and receptivity/spontaneity
Source
Andrew Bowie (German Philosophy: a very short introduction [2010], 2)
Book Reference
Bowie,Andrew: 'German Philosophy: very short intro' [OUP 2010], p.24
A Reaction
I have the impression that there were two strategies: break down the opposition within the self (Fichte), or break down the opposition in the world (Spinozism).