A Noumenon (n.) is not an object of intuition but a problem 'unavoidably bound up with the limitation of our sensibility'.
A Noumenon (n.) is not an object of intuition but a problem that points to the limitation of human sensibility by asking the question as to whether there would be objects for non-human understanding.
Noumenon (n.) is reality, true reality that can never be experienced because our perceptions have distorted it. It is conceivable but not know-able.
The Noumenon (n.) is what one must paradoxically make of oneself as subject of freedom, while remaining, in one's own empirical consciousness, a phenomenon of nature.
The Noumenon (n.) as cause — causa noumenon, a being with free will — is a thinkable but theoretically empty concept, which receives its meaning only from the moral law.