sentences:  By this speculative process, which Günther calls a "metalogical" or ideal ("ideell") inference, as distinct from a logical or conceptual conclusion, the idea of its own being becomes for the soul the most certain of all truths (the Cartesian "cogito ergo sum").Then from the certainty of its own existence the thinking soul arrives at the knowledge of an existence outside itself, since it is confronted by phenomena which it cannot refer to itself as cause, and for which, in line with the ontological inference, it must assign a cause in some real being external to itself.Thus regarding man as a compound of two qualitatively different principles, spirit and nature, he arrives at the knowledge of the real existence of nature.