 Around the end of the eighteenth century, Mitogaku came to address contemporary social and political issues, beginning the era of Later Mitogaku.The ninth Mito clan leader, Tokugawa Nariaki (1800–1860), greatly expanded Mitogaku by establishing the Kōdōkan as the clan school.In addition to Confucianist and kokugaku thought, the school also absorbed knowledge from medicine, astronomy and other natural sciences.