 Trimmer's fundamentalism, Grenby argues, does not necessarily mark her as a rigid thinker. Grenby points out that Trimmer, like Rousseau, believed children were naturally good. In this view, she was arguing against centuries of tradition, particularly Puritanical attitudes towards raising children (exemplified in the doctrine of original sin). Although she attacked Rousseau's works, Grenby argues that she agreed with "Rousseau's key idea, later taken up by the Romantics, that children should not be forced to become adults too early", in particular that they should not be exposed to political issues too soon. Trimmer also maintained that mothers and fathers should share the responsibility of caring for the family. Like the progressive educational reformers and children's authors Maria Edgeworth and Thomas Day and even Rousseau himself, Trimmer opposed rote learning and advocated flexible and conversational lessons that encouraged critical thinking in children. She also promoted breastfeeding (a controversial position at the time) and parental involvement in childhood education.
