An idea posited by this philosopher has been explained by scholars via the “two aspects” and “two worlds” interpretations. In one text, this philosopher argues that certain concepts he analyzes are objectively valid because experience and apperception are only possible through them. This philosopher asserted that morality and freedom are reciprocal through his “reciprocity thesis.” This philosopher said (*) space is not an empirical concept (10[1])and argued we only know the world through its appearances and not through (-5[1])the noumenal “thing-in-itself.” (10[1])This philosopher argued that only maxims that can be willed as a universal law are morally permissible (10[1])through a categorical imperative and, in one book, discussed synthetic a priori propositions. For 10 points, name this German enlightenment philosopher of transcendental idealism and the book Critique of Pure Reason. ■END■ (10[1])