Phylogeny in psychoanalysis is the study of the whole family or species of an organism in order to better understand the pre-history of it. It might have an unconscious influence on a patient, according to Sigmund Freud. After the possibilities of ontogeny, which is the development of the whole organism viewed from the light of occurrences during the course of its life, have been exhausted, phylogeny might shed more light on the pre-history of an organism.