《宋史·列传·卷一百八十六》
周敦颐每每命令他俩探寻孔子、颜子感到快乐的地方，他们感到快乐的是什么事呢，二程的学说渊源就是来自于这里。
敦颐每令寻孔、颜乐处，所乐何事，二程之学源流乎此矣。
Zhou Dunyi often ordered them to investigate where Confucius and Yan Zi felt joy, what made them happy, and the ultimate source of the Ercheng school came from here.