That Śākyamuni Buddha is in us also means we are In Śākyamuni Buddha. In other words, we are living in the Buddha’s life. These phrases show us the meaning that the Buddha and we are united and seen from the Buddha’s perspective, we are also one with him.

Nichiren Shōnin stated in the Kanjin Honzon Shō,

“Śākyamuni Buddha, the Lord-preacher of this Pure Land, has never died in the past, nor will He be born in the future. He exists forever throughout the past, present, and future. All those who receive His guidance are one with this Eternal Buddha. It is because each of our minds is equipped with the ‘3,000 modes of existence’ and the ‘Three Factors,’ namely, all living beings, the land in which they live, and the five elements of living beings.”
(WNS2, page 148)

In summary, according to the doctrine of Hon-In Hon-Ga (true cause and true effect) and Ichinen Sanzen of Ji, a master (the Buddha) and his disciples (beings of nine realms, especially followers of the Lotus Sūtra) are beginningless and endless and one with the Buddha. This is the world of Ichinen Sanzen of Ji.

When we read Chapter 16 of the Lotus Sūtra, “The Duration of the Life of the Tathagata,” we realize that the one great being of the Universe is the Original Buddha Śākyamuni who has warm compassion and personality. Now the philosophical theory of Ichinen Sanzen of Ri has become a warmhearted religion and the understanding of this religion is realized through chanting of the Odaimoku, creating the actual Ichinen Sanzen of Ji.

Enlightenment means awakening to the truth of Ichinen Sanzen and realizing a great life transcending the limits of time and space. Ichinen Sanzen is the wisdom of the Buddha’s enlightenment and the circumstances obtained with His enlightenment. Ichinen Sanzen of Ri is awakening to Ichinen Sanzen as the Buddha’s enlightenment through meditation or mental practice, and the enhancement of one’s own wisdom.

In contrast, our own lives are connected with the Buddha’s life through faith and the Odaimoku. If one can imagine connecting a pipe between the Buddha’s life and ours, Ichinen Sanzen as the Buddha’s wisdom and circumstance of His enlightenment flows naturally into our lives and becomes our own wisdom. We receive Ichinen Sanzen from the Buddha through our chanting of the Odaimoku. This is Ichinen Sanzen of Ji.

Fundamentally, Ichinen Sanzen can be explained as follows: every thought (ichinen) encompasses three thousand (san-zen) worlds which make up the entirety of existence and the universe, or more simply, “the three thousand realms are contained in one mind.” The number 3,000 derives from multiplying the conceptual categories of “the mutual possession of the ten realms,” “the ten aspects of existence” and “the three categories of realms.” These basic concepts describe the states of existence. While “3,000” theoretically represents the existing worlds in the universe, the number is meant to describe vastness, universality, or infinity. Ichinen Sanzen of Ri refers to the theoretical principles found in the theoretical or “shakumon” section of the Lotus Sutra.

The doctrine of Ichinen Sanzen must be considered from two perspectives: the doctrine as taught in the theoretical section (shakumon) of the Lotus Sutra and the doctrine as taught in the essential section (honmon) of the Lotus Sutra. Simply speaking, the theoretical section refers to the first 14 chapters of the Lotus Sutra, which is the realm of the historical Buddha, while the essential section refers to the latter 14 chapters, which is the realm of the Eternal Śākyamuni Buddha who is eternally engaged in the activities of saving living beings. The theoretical section is known as the “Ichinen Sanzen of Ri, ‘ while the essential section is known as “Ichinen Sanzen of Ji

Attaining Buddhahood means to awaken to the doctrine of Ichinen Sanzen and obtain an unlimited-life. We have lost that ability; but we can participate in the Buddha’s activities as a part of His life when we chant the Odaimoku. This is the way for us to attain Buddhahood in Mappō.

Grand Master T’ien-tai awakened to Ichinen Sanzen by practicing spiritual contemplation and insight. He may have meditated while thinking something like, “I was born from my parents. If my parents did not exist, I wouldn’t have existed. In other words, my parents are living in my life. If I trace back my family, there are immeasurable lives living in myself. Not only that but also I have been taken care by innumerable people since I was born. The meals that I ate today are great merits of many farmers’ hard labor. Because of those people, I am able to live my life today. In other words, the lives of those people also exist in my life. We are living in the world based on the culture that was created by people in the past. It means that people in the past who created the culture also live in my life. Not only human but also because of nature such as grass and trees, water and air, and the sun and land, my life has been maintained. However, people in Mappō do not have the same ability as T’ien-tai to awaken to Ichinen Sanzen. Attaining Buddhahood is limited only with Ichinen Sanzen. Following this logic, we wouldn’t be able to attain Buddhahood. With this point as his ultimate conclusion, Säkyamuni Buddha offered us the Odaimoku with his great compassion.