The themes from this book require extending into other research areas. First, the history of political thought and ideas: psychology itself is an idea, since modern political thought emanated not only from thinking about ‘man’ but also from what the thinker believed himself to be, qua man: that is, his interior religious and/or psychological status. Second is the history of education, where the importance of the German-language tradition (Schleiermacher, Herbart, Froebel) might lead to studying the idea of universal salvation as a founding discourse of modern schooling, and the ‘developer’ as the individual embodiment of social and national progress. Third comes disability history, concerning institutions and asylums, which has encouraged a single reified notion of developmental disability; a critical conceptual history should make it possible to stand outside this. The fourth area is literature. The novel is the classic literary ‘form’ of a linear developmental narrative, but its historical examples reveal it to be a constant subversion rather than reflection of the developmental idea, even in the typical novel of personal formation (Bildungsroman).