Mao Collection, Upper Volume
Radical: Heart (xīn)
Character: wu
Kangxi Strokes: 8
Page 377, Entry 15
According to the Correct Character Guide (Zhengzitong), the archaic form of the character for realize (wu) was written with the component for heart and the character for five, but was later abbreviated to the current form. See the detailed entry under the seven-stroke section.