Until now, the analysis of dreams has dealt almost exclusively with their contents and has been concerned with an attempt to extract all their meaning from the images which appear in them. As is well known, the incorporation into science of the analysis of dreams began with Freud, who, upon discovering a basic hypothesis or subject, quickly arrived at a kind of metaphysics of which dreams are the manifestation: the libido, which is, in essence, desire.

But, in dealing with the phenomenon of dreams as a part of human life, one must first study their form: the form of the dream, first of all; later, the species of dreams, if such species exist. One must, that is, arrive at a phenomenology of the dream and of dreams. Such a phenomenology does not exhaust the study of dreams; it is simply a first approach to knowledge of dreams, an introduction.