Day 21 covers all of Chapter 16, The Duration of the Life of the Tathāgata.
Having last month repeated in gāthās why the Buddha expediently shows his Nirvāṇa, we conclude Chapter 16, The Duration of the Life of the Tathāgata.
I can do all this by my supernatural powers.
I live on Mt. Sacred Eagle
And also in the other abodes
For asaṃkhya kalpas.The [perverted] people think:
“This world is in a great fire.
The end of the kalpa [of destruction] is coming.”
In reality this world of mine is peaceful.
It is filled with gods and men.
The gardens, forests and stately buildings
Are adorned with various treasures;
The jeweled trees have many flowers and fruits;
The living beings are enjoying themselves;
And the gods are beating heavenly drums,
Making various kinds of music,
And raining mandārava-flowers on the great multitude and me.[This] pure world of mine is indestructible.
But the [perverted] people think:
“It is full of sorrow, fear, and other sufferings.
It will soon burn away.”Because of their evil karmas,
These sinful people will not be able
To hear even the names of the Three Treasures
During asaṃkhya kalpas.To those who have accumulated merits,
And who are gentle and upright,
And who see me living here,
Expounding the Dharma,
I say:
“The duration of my life is immeasurable.”
To those who see me after a long time,
I say, “It is difficult to see a Buddha.”I can do all this by the power of my wisdom.
The light of my wisdom knows no bound.
The duration of my life is innumerable kalpas.
I obtained this longevity by ages of practices.All of you, wise men!
Have no doubts about this!
Remove your doubts, have no more!
My words are true, not false.The physician, who sent a man expediently
To tell his perverted sons
Of the death of their father in order to cure them,
Was not accused of falsehood although he was still alive.In the same manner, I am the father of the world.
I am saving all living beings from suffering.
Because they are perverted,
I say that I pass away even though I shall not.
If they always see me,
They will become arrogant and licentious,
And cling to the five desires
So much that they will fall into the evil regions.I know who is practicing the Way and who is not.
Therefore I expound various teachings
To all living beings
According to their capacities.I am always thinking:
“How shall I cause all living beings
To enter into the unsurpassed Way
And quickly become Buddhas?”
Nichiren discusses this Sahā world being the Buddha’s Pure Land in his Treatise on Protecting the Nation:
QUESTION: Which “Pure Land” should practicers of the Lotus Sūtra pray to be reborn in?
ANSWER: It is stated in the sixteenth chapter on “The Life Span of the Buddha,” the essence of the Lotus Sūtra consisting of 28 chapters, “I will always stay in this Sahā World;” “I reside here always;” and “This world of Mine is at peace.” According to these statements, the Eternal True Buddha, the origin of all Buddhas in manifestation, is always in this Sahā World. Then why should we wish to be anywhere other than this Sahā World? You should know that there is no Pure Land other than the very place where the practicer of the Lotus Sūtra resides. Why should we concern ourselves seeking a Pure Land in any other place?
Shugo Kokka-ron, Treatise on Protecting the Nation, Writings of Nichiren Shōnin, Doctrine 1, Pages 67-68