 It is already evident in the definition of problems themselves. Three aspects of problems must be distinguished. There is the “statement of the problem” (Problemstellung), its particular and perhaps idiosyncratic characterization; there is the “current state of the problem” (Problemlage), more stable but still historically malleable; and there are the “contents of the problem” (Problemgehalt), including its sometimes nonrational and impenetrable aspects, which are properly “metaphysical.” It is worth quoting at length: