What Sustains the Physical Body in the Four Dhyānas?

When one cultivates to the fourth dhyāna, what phenomena occur in the body? Originally we breathe through the mouth and nose, but now the breathing stops; not only does breathing stop, the beating of the heart and pulse also stops, and the circulation of qi and blood ceases as well. What function do the heart and pulse serve? With each contraction and expansion of the heart, blood is delivered throughout the body, nourishing and moistening it. For the body to function normally, it needs qi and blood; qi drives the blood to circulate back and forth throughout the body. Blood is nutrition, the nourishment required by this machine of our body; without nourishment the machine cannot run. Under normal circumstances, the faster this machine of the body runs, the more nourishment it needs, the more qi and blood it requires, and this demands a more robust function of the heart, so as to ensure the body operates normally. This qi and blood constitute the four great elements the body needs, and the body is composed of the four great elements.

When meditative concentration becomes very deep, the body's operations slow down, the internal organs consume less nourishment, and not so much qi and blood is needed. When the body consumes only a minimal amount of nourishment, with slow metabolism, and no longer needs so much nourishment of the four great elements, breathing stops, and the beating of the heart and pulse also stops. But at this time a small amount of qi and blood is still needed to maintain the existence and functioning of the living organism; it is simply that the body no longer relies on the coarse nourishment of the four great elements from breathing and eating—the four great element particles absorbed through the body's pores from the surrounding air are sufficient, and the body's waste is also expelled through the pores. However, if a person in meditative absorption were placed in a sealed container, he would suffocate to death due to the lack of supply of the four great elements from the air.
The physical body is also composed of the four great elements; the physical body and the surrounding environment mutually merge, interconnect, and influence each other. Material things can also transmit particles of the four great elements to one another, so it can be said that the four great elements of matter are constantly radiating outward, with a quality of mutual perfuming. That is to say, external matter can, through every cell of the body, transmit these material particles, which are then absorbed and become matter within the body, while the matter in the body simultaneously sends particles of the four great elements outward. When this input and output reach a state of balance, the body is normal. The physical body can absorb the nourishment of the external four great elements to sustain the body's operation, so the external material environment can influence the physical body; likewise, the body's four great elements are also sent outward, so the body can also influence the external material environment. Thus there is a certain connection between the bodies of sentient beings, and they can influence one another—let us tentatively call this phenomenon shared karma.

After sentient beings of the desire realm enter the fourth dhyāna, the body relies on the surrounding environment for nourishment; beings of the form realm in meditative absorption also rely on subtle four great elements for nourishment; beings of the formless realm have no physical body, so they no longer need the nourishment of material four great elements. When there is no meditative concentration, the body consumes a great deal of the four great elements as nourishment; the more bodily and mental activity, the more of the four great elements is consumed, and the more qi and blood is needed. People with many wandering thoughts consume more qi and blood and need to eat more food than others; those with few wandering thoughts consume less, and those with little bodily activity also consume less.

We should regard the physical body as a machine—in fact, it is a machine. The operation of this machine requires the consumption of nourishment; for it to function normally, nourishment must be replenished. The faster the machine runs and the greater the workload, the more nourishment it needs and the greater the energy it requires. The energy humans need comes from food and drink, from the material living environment; the machine needs lubricating oil to run. If you want this machine to have longevity, you must reduce its operation and reduce its workload. Because when the machine runs there is wear and tear, which consumes the machine; the more it runs, the more it wears down, and the machine gradually grows old, with all its functions declining. It is the same with people: when a person's level of activity is excessive, the machine of the human body wears down more, and the lifespan becomes shorter.

In meditative concentration a person has very few wandering thoughts, or none at all, and the body is not active; he needs little nourishment, the internal organs are less active, there is less wear and tear, and people with meditative concentration generally have healthy physical bodies and longevity. Modern people do not understand this; they all strive to live well, eat well, and have fun, to enjoy food and drink, not knowing that the more one eats and the richer the nutrition of what one eats, the greater the workload of the body's internal organs and the more severe the wear and tear, and thus the worse the body becomes and the harder it is to live long. Therefore, eating a lot and eating highly nutritious food makes it very difficult for the internal organs to digest and absorb, requiring an enormous workload, so the internal organs are greatly consumed, and longevity is not easy to attain. If you want longevity, you must reduce the body's wear and tear, reduce the workload, reduce the amount of activity, and further cultivate meditative concentration to reduce wandering thoughts.

Meditative concentration can calm the mind; the activity of body and mind is reduced, wear and tear is less, and the lifespan is longer. Once the fourth dhyāna has been attained, the length of one's lifespan is decided by oneself. If one wishes to relinquish one's lifespan early and go to other worlds, such as the heavenly realms, one can decide for oneself; if one does not wish to relinquish one's lifespan early, or wishes to live for a thousand or ten thousand years, that too is decided by oneself, because within the fourth dhyāna there are supernormal powers, and one can freely decide whether to keep or leave the body, with the time of birth and death determined by oneself. But one still cannot be completely at ease, because the view of self has not yet been eradicated and one cannot escape the cycle of the six realms of rebirth; it is only that the birth and death of this life are up to you. Without the fourth dhyāna, one has no mastery over the birth and death of this life—to relinquish one's lifespan early one would have to commit suicide, and whether you wish to live an extra year, half a year, a day, or an hour is not up to you either.

The body is merely an instrument for our cultivation. View it from an objective perspective, take good care of it, but do not cling to it, do not regard it as self or belonging to self; then you can make good use of the body to cultivate the Path, and at the very least the body will not become a burden, dragging us into endless birth and death in the cycle of saṃsāra.