 One of the more distinctive features of the various expressions of Neo-Confucian philosophy in early-modern Japan was their shared emphasis on the importance of doubt in learning. Chinese philosophers from the Song dynasty, from Zhang Zai (1020–1077) through Zhu Xi, emphasized the need for doubt and skepticism in relation to achieving any real progress in philosophical learning. In Japan, doubt came to have notable advocates, first with Hayashi Razan, one of the earliest and most consistent advocates of Neo-Confucianism, and later with Kaibara Ekken (1630–1714), to the end a professed Neo-Confucian, but one who advanced one of the most systematic expressions of philosophical doubt in the early-modern period. With Razan and Ekken, skepticism was never an end in itself, but rather a significant waypoint on the way toward coming to more solid conclusions regarding philosophical questions, and indeed, all matters related to informed engagement in this world.