大乘義章 1.50

1.50

言內外者、義別兩門：一隨相以分、二情理相對。言隨相者，眾生為內、山河大地非情物等以之為外。若當說彼因果之性，局在眾生，得言是內；若說理性，性通內外，雖復約彼內外相辨，而體平等，非內非外。言情理者，即彼妄想陰界入等，以說性故，得言在內。而真平等，妙出情妄，名之為外。故經說言「斷脫異外有為法依持建立者是如來藏。」又經復言「性雖住在陰界入中，而實不同陰界入也。」以不同故，名之為外。不同情取，亦得說為非內非外。故經說言「眾生佛性，非內非外」（此二門竟）。

Regarding 'internal and external', the meaning is distinguished into two aspects: first, dividing according to marks; second, contrasting affective consciousness and principle. Regarding 'according to marks': sentient beings are internal, while mountains, rivers, the great earth, insentient things, and the like are external. If one speaks of the nature of cause and fruition as confined to sentient beings, it may be said to be internal; if one speaks of the nature of principle, the nature pervades internal and external, and although distinguished in terms of internal and external marks, its essence is equal, neither internal nor external. Regarding 'affective consciousness and principle': because nature is spoken of with respect to those skandhas, dhātus, and āyatanas of delusive conceptualization, it may be said to be internal. Yet true equality wondrously transcends affective delusion, so it is named external. Hence the sūtra says: 'That which supports and establishes the conditioned dharmas severed, freed, different, and external is the tathāgatagarbha.' Again, the sūtra also says: 'Although nature abides within the skandhas, dhātus, and āyatanas, it is in truth not identical to the skandhas, dhātus, and āyatanas.' Because it is not identical, it is named external. Because it does not conform to affective grasping, it may also be said to be neither internal nor external. Hence the sūtra says: 'The Buddha-nature of sentient beings is neither internal nor external.' (This concludes the second section.)