大乘起信論義記 2.169

2.169

Question: Only after first attaining self-benefit does one initiate the activity of benefiting others; why is benefiting others spoken of as beginningless? Answer: There are two explanations: First, it is said that in a single thought the Tathāgata responds pervasively to the three times. Because that which is responded to is beginningless, that which can respond is beginningless, just as the complete cognition of a single thought pervasively penetrates the limitless realms of the three times. Because the realms are limitless, the cognition is also limitless; and because the marks manifested by limitless cognition are such, they are able to be beginningless and also able to be endless. This cannot be measured by the deliberations of the mind and consciousness, and is therefore called inconceivable activity. Second, it is said that because avidyā is exhausted, incipient enlightenment is identical with the innate; yet because that innate enlightenment has constantly initiated activities and functions to benefit sentient beings from beginningless ages, incipient enlightenment is identical with it and is therefore also beginningless. Because all buddhas have no distinction, have no new or old, and all lack any difference of incipient enlightenment, and because innate enlightenment is equal, without beginning and without end, they can constantly transform sentient beings; this is the function of tathatā, and is therefore called inconceivable activity.