Benjamin Spock - reference source - 1946 - p. 138    

With American sales second only to the Bible in the twentieth century, Dr. Benjamin Spock’s parenting manual emphasizes the importance of flexibility, maintaining confidence, and trusting in one’s own abilities as a parent. It is generally considered to have revolutionized parenting for the post-World War II era, before which rigidity, routine, and limited displays of affection in childrearing dominated prevailing wisdom. The book sold more than 750,000 copies in its first year; mothers (who were doing the bulk of childrearing) claimed to appreciate its non-patronizing tone and accessible wording. However, feminists in the 1970s criticized its stereotyped notions of gender roles.

Spock was a practicing pediatrician who incorporated aspects of Freudian psychoanalytic theory into his own outlook on breastfeeding and potty-training issues to give his advice a more putatively scientific grounding.