大乘起信論義記 3.163

3.163

○自下第四顯盡不盡義，於中二：初明染法違真，無始有終；後明淨法順理，有始無終。

From here below is the fourth [section], revealing the meaning of exhausting and not exhausting, in which there are two: first, explaining that defiled dharmas contradict the real, being without beginning but having an end; later, explaining that pure dharmas accord with principle, having a beginning but being without end.