妙法蓮華經玄義 8.51

8.51

心是可軌者，若無觀則無規矩，以觀正心王，心王正故心數亦正。行、理亦爾，心王契理，數亦契理，故名可軌也。心常者，心性常定，猶如虛空，誰能破者？又惡覺不能壞善覺，邪行不干正行，邪理不壞正理，故心名常。

As for the mind being that which can be a norm: without contemplation there is no compass or square; by means of contemplation one rectifies the king of mind, and because the king of mind is rectified, the mental factors are also rectified. Practice and principle are also like this: when the king of mind tallies with principle, the factors also tally with principle; therefore it is named that which can be a norm. As for the mind being constant: the nature of the mind is constantly fixed, just like empty space; who can destroy it? Furthermore, evil coarse examination cannot destroy good coarse examination, perverse practice does not disturb correct practice, and perverse principle does not destroy correct principle; therefore the mind is named constant.