妙法蓮華經玄義 5.128

5.128

三、類通三佛性者，真性軌即是正因性；觀照軌即是了因性；資成軌即是緣因性。故下文云：「汝實我子；我實汝父。」即正因性。又云：「我昔教汝無上道故，一切智願猶在不失。」智即了因性，願即緣因性。又云：「我不敢輕於汝等，汝等皆當作佛。」即正因性。「是時四眾，以讀誦眾經」即了因性。「修諸功德」即緣因性。又云：「長者諸子，若十、二十，乃至三十。」此即三種佛性。又云：「種種性相義，我已悉知見。」既言種種性，即有三種佛性也。若知三軌即三佛性，是名理佛性。五品，觀行見佛性。六根，相似見佛性。十住至等覺，分真見佛性。妙覺，究竟見佛性。是故稱妙（云云）。

Third, subsuming and identifying with the three buddha-natures: the track of true nature is precisely the direct cause-nature (正因性); the track of contemplative illumination is precisely the disclosing cause-nature (了因性); the track of auxiliary conditions is precisely the conditional cause-nature (緣因性). Therefore, the text below states: "You are truly my son, and I am truly your father"—this is the direct cause-nature. It also states: "Because I taught you the unsurpassed path in the past, your wish for omniscient wisdom still remains and has not been lost." Wisdom is the disclosing cause-nature; the wish is the conditional cause-nature. It also states: "I dare not despise you, for you shall all become buddhas"—this is the direct cause-nature. "At that time the fourfold assembly, by reading and reciting the various sūtras"—this is the disclosing cause-nature. "Cultivating various merits"—this is the conditional cause-nature. It also states: "The sons of the elder, whether ten, twenty, or even thirty"—these are the three kinds of buddha-nature. It also states: "The meanings of the various natures and marks, I already completely know and see." Since it speaks of "various natures," there are indeed three kinds of buddha-nature. If one knows that the three tracks are precisely the three buddha-natures, this is called the buddha-nature of inherent principle. In the five stages, through contemplative practice, one sees the buddha-nature. In the purification of the six sense-faculties, through semblance, one sees the buddha-nature. From the ten abodes to equal enlightenment, through partial realization of the real, one sees the buddha-nature. In wondrous enlightenment, one ultimately sees the buddha-nature. Therefore it is called wondrous (and so forth).