The “self-nature” of the Lotus Sūtra is not what non-Buddhists think it to be because we possess in our heart all living beings of the Ten Realms. We have in ourselves the realm of Buddhas, let alone those of all living beings. Therefore, to become a Buddha now does not mean to be a new one. The “other-power” in the Lotus Sūtra, too, is not what non-Buddhists consider it to be. For other Buddhas are contained within each of us by nature. They also manifest themselves in us ordinary people. At this point I am omitting a discussion of both the “dual” and “spontaneous” powers.

Ichidai Shōgyō Tai-I, Outline of All the Holy Teachings of the Buddha, Writings of Nichiren Shōnin, Doctrine 3, Page 91