Who is Sigmud Freud from Necessary Losses and what is their importance?

Sigmud Freud is one of the most famous psychologists of all time. He connected almost all of life's patterns with our sexuality and urge to procreate. Viorst quotes Freud extensively and relies heavily on his theories and philosophies throughout her book. She also quotes him on the subjects of love, dying, hatred, narcissism, the Oedipus complex, penis envy, repetition compulsion and sibling rivalry. When Viorst authorized this book, she was a graduate student at Washington Psychoanalytic Institute, whose basis of education is primarily Freudian.