大方廣佛華嚴經隨疏演義鈔 79.107

79.107

疏「三彼因中之果智」下，第三自他交徹。謂諸凡夫因中果智，即他諸佛已成果智。自身佛性，一身竪論；他佛智在凡，自他橫辯，故更玄也。

Regarding the Commentary's statement from "Third, that fruit-wisdom within the cause..." onward, this is thirdly the mutual interpenetration of self and other. It means that the fruit-wisdom within the cause of ordinary beings is precisely the already-achieved fruit-wisdom of other buddhas. One's own buddha-nature is discussed vertically within a single body; another buddha's wisdom being present in ordinary beings is discussed horizontally between self and other, and hence it is even more profound.