In honor of International Holocaust Remembrance Day, we are telling the story of Margarethe Hilferding, a pioneering psychoanalyst and physician from Vienna who was murdered in a Nazi concentration camp in 1942. She was the first woman to earn a medical degree at the University of Vienna and the first woman to join Sigmund Freud’s Vienna Psychoanalytic Society. In her paper On the Basis of Mother Love, presented to the society in 1911, she argued that the maternal instinct is not innate but can develop after birth, a theory Freud and the rest of her male colleagues rejected. Margarethe soon left the society and devoted much of her life to treating women in working class neighborhoods and advocating for their reproductive health. Her theory of maternal instinct remains controversial even today.