菩薩瓔珞本業經 1.59

1.59

「佛子！六、佛教化力。所謂十二入：外六境到內六根，為識所入處，故名為入。其慧觀者，不在內、不在外、不在中間，一切法無自無他故。

"Buddha-son! Sixth is the power of the Buddha's teaching, that is to say, the twelve bases: the six external objects reach the six internal sense faculties and serve as the places into which consciousness enters, and so they are called bases. As for contemplation with wisdom: it is not internal, not external, and not in between, because all phenomena have neither self nor other.