The twenty seventh chapter of the sequel tantra of the Four Tantras states:
This body of a living being is formed from the four elements, the illness to be healed is created by the four elements, and the nature of the medicinal remedy is the four elements: thus the body, illness, and remedy are integrally connected.
The four elements here being referred to are the four mahābhutas, as they are known in Sanskrit, i.e. earth, water, fire and air. The English term "element" does not really cover the range of the term "bhūta" (Tibetan 'byung ba), which carries the meaning of "having been produced". In this context, the four elements are considered to be the primary components of all material things.
When considering the external four elements, the most coarse aspect of physical reality, we need to understand their characteristics. The characteristic of earth is solidity; water is liquidity, moistness; fire is heat; and wind is motility. All material objects possess all four of these qualities in some measure. The function of these four elements is symbolized by the colors gold, white, red and green respectively (space is symbolized as blue since it represents the immutability of the sky). Earth (Sans. pṛthvi, Tib. sa) is symbolized by gold because it is heavy, hard, shiny, and so on, like gold. Water (ap, chu) is symbolized by white because the color of clouds in the sky which are its source. Fire (agni, me) is symbolized by red is because of the red glow of burning materials. Air (vāyu, rlung) is symbolized as green because of it's activity of moving leaves and plants which do not move on their own.
These four elements go into the make of the human body, but not directly. The bodies of living beings are made up of the refined form of the four elements. We consume other life forms, especially plants, that are capable of transforming the raw elements into refined elements which are suitable for us to eat.
Not only that, but also when we consider the winds that course through the body and regulate sensory functions, the elements are present in those winds in an even more refined manner. And finally, we can understand that since the winds and the mind are inseparable, the four or five elements are even present in consciousness. Based in this understanding, if we are advanced yogins and understand the principles of jn̄ānavāyu, wisdom winds, we can directly sustain our bodies by drawing the most refined nature of the five elements directly from our breath. Every thirty third breath that we take is a so-called "wisdom breath" and through this breath we directly absorb the most refined essence of the five elements. This means that out of the 21,000 breaths that we absorb daily, 636 of those breaths are wisdom breaths. If we develop the capacity to hold our breaths in a yogic practice called Kumbhakha or vase-breathing, we can maximize the absorption of the pure five elements, directly support our life-sustaining fluid known in Sanskrit as ojas (Tib. mdangs or gzi can mdangs) and extend our lifespan.
To understand this, we need to examine the exoteric as well as the esoteric accounts of the conception of humans beings according to both the Four Tantras and the tantras of Secret Mantra (Francis M. Garret has written an excellent book covering the vast majority of conception schemes current in Tibetan Buddhism). When we understand how the human body is formed, we are then in a position to understand how the four or five elements contribute to states of health and illnesses in the human body, and what type of medicine and therapy may be used to either maintain the body in a state of constant health or remedy any of the treatable illnesses that may arise in the body.
To begin with, the second chapter of the explanatory tantra states:
First, a man and women’s non-defective semen and blood and a consciousness having been driven action and affliction, the cause of conception in the womb.
To clarify this, non-defective means that both mother's blood and the father's sperm contain a full complement of the five elements in a balanced fashion, otherwise the reproductive material in question will be defective. However, the presentation of the elements is not complete with this explanation. Acharya Vagbhata states in the first chapter of the Foundation of the Body (Śārīra śthana) of the The Autocommentary (Aṣṭāṇgahridayavaiduryaka-bhaṣyaṃ):
If it is asked how sentient beings are born, first, the semen and blood of the father and mother lacking defects of air and so on, and consciousness possessing action and affliction (simultaneously occurring with which are the very subtle components of the five primary elements, space and so forth which is an object for yogins beyond objects of the senses) assemble and collect in the womb in an instant...
Therefore, we can understand that these very subtle primary elements are the five elements associated with srog chen po rlung (*mahāprāṇavāyu) i.e. great life wind, which, Professor Tamdrin Gyal explains, is the basis upon which the ālayavijñāna, the all basis consciousness (ālayavijñāna), is mounted.
All of these elements are refined elements in the sense that they are not in their primary or coarse form. The material elements that come from the father and mother are refined out of the food that they ate during the seven stage process of digestion which results in the reproductive substances formed from the body, as well as the element winds that are innate within the life wind.
The Heart of the Ḍākinī states:
...the non-defective material of the father and mother and the grasper of that mix into one, is enclosed by the womb, and becomes tangible. Since the wind/mind that appropriates the body mixes with egg in the bindu of the father and the mother, those causes and conditions become the functions of the relative four elements (earth, water, fire and air). The wind and mind become the function of the four ultimate elements (earth, water, fire and air).
Now then, refined matter is not just confined to sentient living beings, but also the matter which makes up plant life is also refined matter i..e matter that is taken up and transformed in a process of plant metabolism as well.
In general, as noted above, we human beings have very little capacity to incorporate the five elements directly, especially earth and fire. Nevertheless, in order to maintain the health of our bodies, we need to replenish the balance of the elements within our bodies otherwise we become ill. When we are hungry, we have an imbalance of wind in our bodies; when we are thirsty, we have an imbalance of fire. To correct that imbalance, we need to eat food for the earth element and drink beverages for the water element. When the elements of the body become pathologically imbalanced, we experience diseases of various kinds, depending upon what elements are thrown out of balance by the four causal conditions that lead to illness i.e. insufficient, excess or incorrect diet, behavior, and seasons, and harmful influences from other beings.
In order to express how the four elements function in the human body, we condense the four elements in three active principles (doṣa, nyes pa) that function within the body: air that functions in the body is termed vata (Tib. rlung); fire, pitta (mkhris pa), and water and earth combined form kapha (bad kan). Now, there is an important point here: the four elements are listed in the order that they form when the this present universe arose i.e. wind, fire, water, and earth. At the time of conception, the second chapter of the explanatory tantra states:
No formation without earth, no cohesion without water, no maturation without fire, no development without air, and no room for development without space.
In the order of conception, the first element, space can be considered the antarābhava or bardo; the element of air is present accompanying the consciousness seeking rebirth. The element of fire is found in the passion of the conceiving couple. The element of water is present within their reproductive fluids. The element of earth is present in the formation of the embryo. At this point, the five elements are fully active and present within the nascent human body and each then plays the role described in the explanatory tantra citation above. Again, when we die, as the seventh chapter of the explanatory tantra explains:
Since the function of earth dissolves into water, one cannot see form. Since the function of water dissolves into fire, the cavities dry out. Since the function of fire dissolves into air, warmth collects [into the heart]. Since the function of air dissolves into space, external breath ceases.
The elements of body dissolve into one another just as the elements dissolve finally at the end of the universe, solidity vanishes, then liquidity, then heat, then motility and all dissolves into a state of rest and separation in unobstructed space until the movement of the minds of sentient beings stir the air element into action again and the whole process of samsara manifests once more on a cosmic scale. This relationship between the outer universe and the inner body is termed a "melathesia" i.e. drawing a correspondence between functions and organs of the inner body with cosmic bodies or processes.
Therefore, in this respect, the three doṣa of vata, pitta and kapha are ordered in the same order as the creation of the elements in the universe.
The most elementary definition of health and disease in Indo-Tibetan Medicine is therefore defined as the unaltered (avikrita, rnam par ma gyur) or altered state of the doṣa (vikrita, rnam par gyur ba), as the Aṣṭāṇgahridayasamgraha states:
Through those being altered or unaltered, the body is destroyed or persists.
Candrananda defines "altered" and "unaltered" in Moonrays (Pādarthacandrakaprabhāvatināma- aṣṭāṇgahridayavritti):
Vāta and so on shift and move elsewhere from their own nature because they are altered, destroying and harming the body. Since [they] are unaltered and remain normally balanced in their own nature, the body persists and is given life.
And the second chapter of the root tantra further explains:
The cause of the body's persistence or destruction comes from the non-alteration or alteration of the trio of the humors, physical constituents, and wastes.
Having understood that health or disease of the body is a function of the balance or imbalance of the three doṣa, and ultimately, the balance or imbalance of the five elements, we then need to understand how to apply remedies based upon the five elements.
In general, the simplest approach to therapeutic remedies is divide all diseases into hot and cold, understanding that fire is the basis of all diseases of heat; and earth, water and wind are the basis of all diseases of cold. But this is not sufficient for understanding diseases and their cure, and for this reason, in Indo-Tibetan Medicine, we try to treat the three humors and their fifteen subdivisions and bring them all back into a state of harmonious balance.
When we condense everything in Indo-Tibetan Medicine, therefore, ultimately, we find the root of health and illness can be found in the five elements that make up the human body.
If we extend our analysis a little further, we can include the role consciousness plays in health and illness. The reason for this is that the action of the three doṣa is governed and comes from the three afflictions that accompany the mind stream and keep us with the cycles of rebirth in samsara. And as we saw above, since the mind and the wind that serves as its mount are inseparable, the mind/wind also possess the function of the five elements. In this fashion then, we can understand how all the elements defined by the Buddha above play a role in health and illness. The ultimate key to health and well-being is the eradication of the three afflictions (kleśas) desire, hatred and confusion, but that discussion will be left for another day.