根本門第三
Chapter 3: The Fundamental Gate
問：萬行為因乘、眾德為果乘。此論但明空義，云何釋大乘耶？答：此論明於乘本。乘本若成，乘義則立。言乘本者，所謂諸法實相。契斯實相則發生般若，由般若故導成萬行，皆無所得能動能出，故名為乘。又今明實相則具萬德，對虛妄故名之為實；用之為身，目為法身；諸佛以此為性，稱為佛性；遠離二邊，名為中道；照無不淨，目為般若；累無不寂，稱為涅槃。故但明實相，即萬義皆圓。問：云何悟此實相？答：以十二種門通於實相，令諸眾生從一一門得悟實相。又乘有三種：一乘因、二乘緣、三乘果。乘因者，所謂實相；乘緣者，即是萬行；乘果者，謂如來法身。問：何故但明此三？答：由實相故萬行成，萬行成故果德立，要須辨三。問：何處有此三文？答：《攝大乘論》明乘有三：一者性乘，謂真如；二隨乘，即萬行；三得乘，謂佛果。此三猶一體，但約時故分三，即是三種佛性義，性乘謂自性住佛性；隨乘謂引出佛性，修於萬行引出因中佛性；三果乘則果德佛性。此三佛性釋《涅槃經》甚精，是故《涅槃經》或時明佛性是果、或時明是因、或明佛性是空。此論正釋於空，則是釋根本佛性。故《涅槃》云「佛性者名為一乘」。今既釋一乘，即釋佛性。問：三論但明空義，正可釋於《大品》，云何解佛性一乘？答：三論通申大小二教，則大乘之義悉在其中，豈不明一乘佛性？問：何處有明一乘佛性文耶？答：《中論．四諦品》云「世尊知是法，甚深微妙相，非鈍根所及，是故不欲說。」此即《法華》之文。《法華》還序初成道時華嚴之事，明知《華嚴》、《法華》顯在《中論》之內。又偈云「雖復懃精進，修行菩提道，若先非佛性，終不得成佛。」長行釋云「如鐵無金性，雖復鍛鍊，終不得成金。」即佛性文也。〈觀如來品〉明法身絕四句、超百非，與《涅槃經．金剛身品》更無有異，即法身文也。
Question: The myriad practices are the cause vehicle, and the accumulation of virtues is the fruit vehicle. This treatise only clarifies the meaning of Emptiness—how does it explain the Great Vehicle?
Answer: This treatise illuminates the foundation of the vehicle. If the foundation of the vehicle is established, then the meaning of the vehicle stands. What is meant by the foundation of the vehicle? It is the true nature of all phenomena. By realizing this true nature, one gives rise to wisdom (*Prajñā*). Through wisdom, the myriad practices are guided to fulfillment—all accomplished without grasping, able to move and transcend. Hence, it is called the vehicle.
Moreover, illuminating the true nature encompasses all virtues. In contrast to the illusory, it is called "true." Used as the body, it is called the Dharma Body. All Buddhas take this as their nature, known as Buddha Nature. Transcending both extremes, it is called the Middle Way. Illuminating without any impurity, it is called wisdom. Quelling all afflictions without remainder, it is called Nirvana. Therefore, by merely clarifying the true nature, all meanings are perfected.
Question: How does one awaken to this true nature?
Answer: Through twelve approaches leading to the true nature, enabling all sentient beings to awaken to it through any single approach. Furthermore, the vehicle has three kinds: the cause vehicle, the condition vehicle, and the fruit vehicle. The cause vehicle is the true nature; the condition vehicle is the myriad practices; the fruit vehicle is the Tathāgata's Dharma Body.
Question: Why only clarify these three?
Answer: Because through the true nature, the myriad practices are accomplished; through the accomplishment of the myriad practices, the fruition of virtues is established. Thus, these three must be distinguished.
Question: Where in the scriptures is this threefold teaching found?
Answer: *The Summary of the Great Vehicle* states that the vehicle has three aspects: first, the nature vehicle, which is Suchness; second, the practice vehicle, which is the myriad practices; third, the attainment vehicle, which is the Buddha's fruition. These three are one in essence but divided by time, corresponding to the threefold meaning of Buddha Nature. The nature vehicle is the Buddha Nature abiding in itself; the practice vehicle is the emergent Buddha Nature, cultivated through myriad practices to bring forth the inherent Buddha Nature; the fruit vehicle is the Buddha Nature as realized virtue.
This threefold Buddha Nature excellently explains *The Nirvana Sutra*. Thus, *The Nirvana Sutra* sometimes describes Buddha Nature as the fruit, sometimes as the cause, and sometimes as Emptiness. This treatise specifically explains Emptiness, which is to explain the fundamental Buddha Nature. Hence, *The Nirvana Sutra* says, "Buddha Nature is called the One Vehicle." Since we now explain the One Vehicle, we are explaining Buddha Nature.
Question: The Three Treatises only clarify the meaning of Emptiness—they may explain the *Perfection of Wisdom Sutra*, but how do they address Buddha Nature and the One Vehicle?
Answer: The Three Treatises universally elucidate both the greater and lesser teachings, so the meaning of the Great Vehicle is fully contained within them. How could they not clarify the One Vehicle and Buddha Nature?
Question: Where is there scriptural support for the One Vehicle and Buddha Nature?
Answer: In *Fundamental Verses on the Middle Way*, the chapter on the Four Noble Truths says, "The World-Honored One knew this Dharma, profound and subtle in its characteristics, beyond the reach of dull faculties, and so initially declined to teach." This corresponds to the *Lotus Sutra*. The *Lotus Sutra* in turn recounts the events of the *Avataṃsaka Sutra* at the time of the first awakening. Clearly, the *Avataṃsaka Sutra* and the *Lotus Sutra* are evident within the *Middle Way* treatise. Furthermore, the verse states, "Though one diligently strives, practicing the path to Enlightenment, if one lacks Buddha Nature from the outset, one will never attain Buddhahood." The prose explanation says, "Just as iron without the nature of gold, even with repeated forging, can never become gold." This is the scriptural support for Buddha Nature. The chapter "Contemplating the Tathāgata" explains that the Dharma Body transcends the four propositions and surpasses the hundred negations, identical to the "Adamantine Body" chapter of *The Nirvana Sutra*—this is the scriptural support for the Dharma Body.