The second book concerns the initial interactions of the child with the world. Rousseau believed that at this phase education should be derived less from books and more from their interactions with the world, with an emphasis on developing the senses, and the ability to draw inferences from them. Rousseau concludes the chapter with an example of a boy who has been successfully educated through this phase. The father takes the boy out flying kites, and asks the child to infer the position of the kite by looking only at the shadow. This is a task that the child has never specifically been taught, but through inference and understanding of the physical world, the child is able to succeed in his task. In some ways, this approach is the precursor of the Montessori method.
Montessori education spread to the United States in 1911 and became widely known in education and popular publications. However, conflict between Montessori and the American educational establishment, and especially the publication in 1914 of a critical booklet, The Montessori System Examined by influential education teacher William Heard Kilpatrick, limited the spread of her ideas, and they languished after 1914. Montessori education returned to the United States in 1960 and has since spread to thousands of schools there. Montessori continued to extend her work during her lifetime, developing a comprehensive model of psychological development from birth to age 24, as well as educational approaches for children ages 0 to 3, 3 to 6, and 6 to 12. She wrote and lectured about ages 12 to 18 and beyond, but these programs were not developed during her lifetime.