[P]reaching the sixteenth chapter of the Lotus Sūtra, the Buddha declared, “All the gods, men, and asura demons believe that this Śākyamuni Buddha was the one who had left the palace of the Śākya clan and sat in meditation under the bodhi tree not far from the town of Gayā and attained perfect enlightenment.” This declaration in the Lotus Sūtra represents what all the great bodhisattvas had in mind while listening to the sūtras starting with the Flower Garland at the Hall of Enlightenment to the fourteenth “Peaceful Practices” chapter of the Lotus. “To speak the truth, good men,” continued the Buddha, “it has been countless aeons (numerous hundreds, ten thousands, 100 millions, nayuta of kalpa) since I obtained Buddhahood.”
Thus with one stroke He denied as untrue all His previous statements such as “obtaining the first enlightenment” said three times in the Flower Garland Sūtra, “the first enlightenment” in the Āgama sūtras, “the first meditation under the bodhi tree” in the Vimalakirti Sūtra, “sixteen years after the first enlightenment” in the Sūtra of the Great Assembly, “I once sat in meditation at the place of practice in Buddhagayā” in the Great Sun Buddha Sūtra, “for twenty-nine years since His enlightenment” in the Sūtra of the Benevolent King, “I once meditated under the bodhi tree in the place of enlightenment for six years” stated in the Sūtra of Infinite Meaning, and “At first I sat at the place of enlightenment, gazed on the tree, and walked about it meditating” in the “Expedients” (second) chapter of the Lotus Sūtra.
Thus it was revealed that Śākyamuni had long been the Buddha since the eternal past, and it became clear that various Buddhas were all manifestations (funjin) of Śākyamuni Buddha. In the pre-Lotus sūtras, as well as in the theoretical section of the Lotus Sūtra, various Buddhas and Śākyamuni Buddha were on the same level, each practiced Buddhism on their own. Therefore, those who considered various Buddhas to be their Most Venerable One did not worship Śākyamuni. Now, however, as Śākyamuni proved to be the Eternal Buddha, those Buddhas on the lotus petals in the Flower Garland Sūtra, or Buddhas in the Hōdō sūtras, Wisdom and Great Sun Buddha Sūtras all became subordinates of Śākyamuni Buddha.
Kaimoku-shō, Open Your Eyes to the Lotus Teaching, Writings of Nichiren Shōnin, Doctrine 2, Page 74