 In 1937, the 6th International Montessori Congress was held on the theme of "Education for Peace", and Montessori called for a "science of peace" and spoke about the role of education of the child as a key to the reform of society.In 1938, Montessori was invited to India by the Theosophical Society to give a training course, and in 1939 she left the Netherlands with her son and collaborator Mario.An interest in Montessori had existed in India since 1913, when an Indian student attended the first international course in Rome, and students throughout the 1920s and 1930s had come back to India to start schools and promote Montessori education.