The Sūtra of Meditation on the Universal Sage Bodhisattva, considered to be the epilogue to the Lotus Sūtra, declares: “This Mahāyāna sūtra is each Buddha’s treasure store, the true intention of all the Buddhas in all the worlds in the universe of the past, present and future, and it is the seed that gives rise to all the Buddhas of the past, present and future;” and “This Mahāyāna sūtra is the eye of each Buddha and each Buddha is provided with the five eyes by this Mahāyāna sūtra. The threefold body of the Buddha is produced by this sūtra. This sūtra contains all Dharmas just as the great ocean contains all water. The immaculate threefold body of the Buddha is produced by this ocean-like sūtra. The three aspects of the Buddha’s body are like a field where gods and human beings can plant merit, and they are the first among those who are worthy to receive offerings.” According to these sūtra passages, the Buddha is born to the Lotus Sūtra, which is like a mother who gives birth. The Buddha is the body and the Lotus Sūtra is the spirit. Therefore, the eye-opening ceremony for portraits and wooden statues of the Buddha should be done with the Lotus Sūtra.

Honzon Mondō Shō, Questions and Answers on the Honzon, Writings of Nichiren Shōnin, Doctrine 2, Page 261-262