The middle part of Vassa was folded back.

SN 13:1
Nakhasikhā Sutta 
tip of nail

I heard it like this.
At one time, the Blessed One was staying near Savati in Jeta's Grove, the monastery of Anatapinika. 

Then the Blessed One, picking up a little dust with the tips of his fingernails, said to the bhikkhus: 

“What do you think, Bhikkhus? Which is bigger, a small piece of dust that you pick up with the tip of your fingernail or the big earth?”

“The great Earth is far greater, Lord. The speck of dust that the Blessed One picks up with his fingernails is hardly a thing. It's not even one ten thousandth of a millionth, it's just this tiny speck of dust that the Blessed One picked up with his fingernails."

“Similarly, Bhikkhus, for the holy disciple, the breakthrough individual, from the point of view of perfection, the suffering and stress is completely over, and what has been annihilated is much greater, with only a maximum of seven rebirths left; There is almost nothing left. It is not 1/100, 1/1000, 1/100,000 when compared to the previous mass of suffering. Monks, the benefits of realizing the Dhamma That's how great it is. That's how great the benefits of acquiring Dharma eyes are."

13.1 note

This is a sermon given to the Buddha’s disciples.

This explanation was given through figurative expressions, and it is difficult for ordinary people to understand its true meaning. The only keywords are “realization of the law” and “up to seven reincarnations.”

Using this keyword, a bhikkhu who has become a monk can clearly understand that the sermon is intended for “those who have entered the stream.”

The ultimate goal of primitive Buddhism, the original words and teachings of the Buddha, is awakening and liberation.

It can be expressed in words such as “awakening” and “liberation” so there is no one in the general public who does not know about it. However, people in the world do not know what that condition is like.

There are four stages from awakening to liberation according to Buddha’s teachings.

The first stage is the aforementioned “those who have entered the stream,” the second stage is “those who once return,” the third stage is “those who do not return,” and the final stage is “those who are far away,” or “arhats.” .

What is Buddhism?

Train with this ultimate state as your goal.

That’s just it.

So what is the final destination?

This is “Nirvana” and those who reach it become “immortal” or physically “non-regenerate.”

This is the end of reincarnation.

In practice, before we enter the gradual stream of time, mental behaviors such as suffering, sadness, melancholy, worry, impatience, fear, and regret decrease. This is the result of such a change in the activity of the cerebrum itself, which controls mental behavior.

Physically, breathing becomes severely reduced, leading to apnea or near apnea. From a common biological perspective, the severe reduction in respiration causes the dissolved oxygen concentration in the blood to decrease.

However, practitioners at this stage maintain an SpO2 rate of 97-98% during meditation.