Abstract: InLectures on Metaphysics,Kant explicated the dual implications of the natural object and the essence in the word “nature”.Though the “heterogeneous puzzle” had not been solved,Kant,in the second edition of  Critique of Pure Reason(1787),proved that the law of cognition is derived from human nature;hence,he overcame the dual opposition between natural science and humanity,and between fact and value.

Key words: Kant, nature, transcendental deduction of category, dual opposition