By Hu Xuezhi
There has long been a tale telling a Buddhist who, once upon a time, summed up his experiences through long-time silent exercise, saying, "My form is a peepul trunk, my heart is as clean as like a looking-glass. I have been dusting my heart every now and then lest it should incur even one slight stain." Upon this, Liu Chu, a great saint, at once pointed to the depth of the truth, saying, "Originally, there existed no tree called peepul, nor a mirror. When there was nothing at all, how to incur dust?"
An analogy can be applicable to explaining the relation between heart and pre-heaven nature. The heart works as like earth, while our nature the emperor. Or in other words, our heart serves as like a vast territory while our nature the king holding reins over it.