Kant's answer is that they correspond to the distinction between two worlds, the world of sense and the transcendental or Supersensible world.
"Edward Caldwell Moore Outline of the History of Christian Thought Since Kant"
Edward Moore
They deny the existence of invisible and Supersensible things.
"The Progressionists, and Angela."
Conrad von Bolanden
Political interests, social obligations, financial concerns, choke the spiracles of our inner being, and we lose all concern about what is Supersensible, and hold no communication with it.
"Castles and Cave Dwellings of Europe"
Sabine Baring-Gould