大乘起信論義記 2.182

2.182

第二因熏中釋內有二因義：初、能作現法之因；二、作內熏之因。亦可初是因義，後是熏習義，故云因熏習也。言如實不空者，此總出因熏法體，謂有自體及性功德故。

In the explanation of the second, 'perfuming as cause,' internally there are two meanings of cause: first, the cause capable of producing manifest phenomena; second, the cause that performs internal perfuming. It may also be that the former is the meaning of 'cause' and the latter is the meaning of 'perfuming,' hence called 'perfuming as cause.' As for stating 'truly non-empty,' this generally presents the substance of the phenomenon of perfuming as cause, meaning that it possesses an own-substance and the virtues of its nature.