Chen Collection, Middle Volume. Radical: Tree (mù). Kangxi strokes: 15. Page 549, Entry 22. According to Tang Rhyme (Tangyun), Collection Rhyme (Jiyun), and Rhyme Gathering (Yunhui), the pronunciation is su. Originally written as su. Jade Chapter (Yupian) states: Su is a horse trough. It is a device for raising horses. In the work of Yangzi, Dialects (Fangyan): A trough is called su in the regions between Liang, Song, Qi, Chu, and Northern Yan. It is also called a zao. It is also used interchangeably with a variant form (tong). School Sayings of Confucius (Jiayu) states: Yan Shuzi lived alone. A neighbor woman's house collapsed, so Shuzi took her in and held a candle until dawn. When the fuel was exhausted, he replenished the torch. The commentary notes: It is also written as su. The character su is derived from the character for working.