In her book, The Female Brain, Louanne Brizendine describes the stages that the female brain goes through during life, citing brain structure and chemistry as the departure for differences between the male and female brains. Most of the misunderstanding of female psychology, Brizendine notes, stems from the misconception held by scientists during most of the 19th and 20th centuries - “that women are essentially small men in psychology and physiology”. She says that it is important to make the distinction between male and female psychologies because physiological sources for these differences do exist, contrary to the reality that they are usually just brushed off as mere deviations during studies.