Things-in-Themselves

What things are independent of how they appear to us. Forever unknown.

Kant's Ding an sich. Our minds structure experience through forms (space, time) and categories (causation, substance). We can therefore only know things as they appear to a mind structured like ours. Things in themselves — what they are independent of our structuring — are systematically beyond reach. Schopenhauer, Nietzsche, and Heidegger all wrestle with this verdict.