But the collective unconscious lies beyond the conceptual limitations of individual human consciousness, and thus cannot possibly be encompassed by them. We cannot, therefore, make controlled experiments to prove the existence of the collective unconscious, for the psyche of man, holistically conceived, cannot be brought under laboratory conditions without doing violence to its nature. [...] In this respect, psychology may be compared to astronomy, the phenomena of which also cannot be enclosed within a controlled setting. The heavenly bodies must be observed where they exist in the natural universe, under their own conditions, rather than under conditions we might propose to set for them.