Kant unveiling the cosmic realm We never see the world in all the possibilities that it is. Immanuel Kant, in his Critique of Pure Reason , calls this the distinction between phenomena  — the world as it appears to us — and the noumena , or the “thing-in-itself” that exists beyond our perception. No matter how hard we try, the thing-in-itself is forever behind the curtain . Even our senses, reasoning, and logic act as filters. The cave isn’t a literal prison. It’s built into