The Will to Power · Friedrich Wilhelm Nietzsche
554.
It is obvious that neither things-in-themselves _nor_ appearances can be related to each other in the form of cause and effect: and from this it follows that the concept "cause and effect" is _not applicable_ in a philosophy which believes in things-in-themselves and in appearances. Kant's mistake--... As a matter of fact, from a psychological standpoint, the concept "cause and effect" is derived from an attitude of mind which believes it sees the action of will upon will everywhere, which believes only in living things, and at bottom only in souls (not in things). Within the mechanical view of the world (which is logic and its application to space and time) that concept is reduced to the mathematical formula with which--and this is a fact which cannot be sufficiently emphasised--nothing is ever understood, but rather _defined_--deformed.
Text from Project Gutenberg, public domain in the United States.