The author examines the oneiric activity in a neuropsychologic prospect, as he considers this approach as valid and capable of giving good results for the understanding of psychic phenomena. After explaining synthetically the principles of the psychophysiologic school of Chicago, of the neuro-physiologic school of professor M. Jouvet in Lyon, and the theoretic hypotheses derived from clinical knowledge like that of the neurologist O. Sacks, the author develops Jouvet's principle of the dream as "endogenous phylogenetic learning". The author is of the opinion that the dream, from a psycho-biological standpoint, has such features that it can be considered as a process that is very similar to the creative one, as intended by S. Arieti, and that has its roots in the "homo naturalis". The oneiric activity seems to be able to implement a creative synthesis between nature and culture, between soma and psyche, between rational world and archetypalinstinctive world, in compliance with the fundamental creative process on which the evolution is based, as explained by K. Lorenz and Teilhard de Chardin with the expressions "unity from diversity" and "créer c'est unir". Therefore, it can be an instrument capable of helping the contemporary man, whose identity is threatened by the excessive discrepancy between the rational conscious process, that is conditioned by the extremely quick cultural transformation (mainly due to technology) and the unconscious archetypal-instinctive process, which is connected with the slow phylogenetic evolution.