妙法蓮華經玄贊 3.157

3.157

Second, demonstrating has the meaning of sameness, because the dharmakāyas of the three vehicles of śrāvakas, pratyekabuddhas, and buddhas are equal. That the dharmakāyas are equal is because the dharmakāya of buddha-nature has no differentiation. The Nirvāṇa Sūtra says: "For example, milk cows have various colors, but when their milk is milked and put in one place, its white color has no difference; buddha-nature is also like this: although sentient beings have various differences, buddha-nature is without difference." The meaning expounded here is that the dharmakāyas of the three vehicles are originally equal; sentient beings do not know this and are unwilling to cultivate and realize the perfection of the dharmakāya. The buddhas appear in the world wishing to demonstrate to sentient beings that this nature of the Buddha's knowledge and vision is shared equally by the three vehicles without duality, causing them to realize it together to completion so as to accomplish the dharmakāya.