In his therapies he examined the imagery of dreams. These related to the collective unconsciousness. By contact with the collective unconsciousness the dreamer has access to the knowledge acquired by mankind over millennia. The collective unconsciousness uses a language of images known as archetypes. The archetypes appear in personified or symbolic picture form.
Archetypes are the basic forces of the universe, and represent typical fundamental experiences.
As the basic building blocks of experience they are of necessity limited in number, but when combined, the archetypes represent the sum total of the inherent potential of the human psyche. This is a huge inexhaustible treasure house of ancient knowledge dealing with the most profound relations between man and the cosmos.