For, metaphysics relates to the grasp of life, which does not directly relates to the synthetic a priori judgment of mathematics or physics. If we are determined by natural necessity, we have no freedom as if it were the action of insect dominated by regulated instinct. If there is no freedom of will, there is no room for choice, where there is no responsibility. However, even if the choice is not a complete obedience to moral law, we can still choose our direction towards moral perfection. Hence there is morality and also freedom.
Freedom belongs to our rational side, while necessity belongs to our sensible side.
Freedom is the self-cause that can intend in any way a purpose for life. Kant's human being is torn between the sensible being and the rational being. The sensible side tends to follow inclination and impulse, while the rational side tries to respond to moral law. The Paradigm of Christ gives clearer view how this human situation occurs. In the diagram of the Paradigm of Christ, life develops itself through the diametrical movement of division and unity.