 Reflecting the inequalities of the day, Itō Jinsai challenged the orthodox Neo-Confucian view by asserting that human nature is simply the physical disposition (kishitsu) that each person is born with. In formulating this view, Jinsai was essentially agreeing with Dong Zhongshu (ca. 179–104 B.C.E.), who defined human nature as “the inborn disposition” of each person. But Jinsai also sympathized with the thinking of Zhou Dunyi (1017–1073), a Song philosopher who is often considered an early exponent of the Neo-Confucian philosophy that found its most complete form in the thought of Zhu Xi. Zhou Dunyi differentiated five natures including the morally strong, the immorally strong, the morally weak, the immorally weak, and the mean which relies on neither strength or weakness.