Prior to people like Margaret Mahler and John Bowlby, psychoanalysis had largely relied on the process of reconstruction to understand child development. In other words, ideas of child development were based on observations of adult patients. In order to understand the problems of their adult patients, Freud and his followers reconstructed the childhoods of their patients. The most severe psychopathology was assumed to reflect regression to the earliest stage of childhood. Less severe psychopathology was assumed to reflect regression to later stages in childhood (like the Oedipal complex). There was very little direct observation of actual children. Although Mahler grounded her ideas in accepted psychoanalytic theory, she added the actual observation of real children. It is perhaps no surprise, then, that the parts of her theory that are based on real observation have had the most staying power, while the parts derived from purely theoretical assumptions have been much less influential.