16 Aug Sin, Virtue, Plant Medicine & Epidemics
Note: While much of this article is about plants and medicine, all these ideas apply equally to animals and food. Treating animals as commodities, packing them into unnaturally crowded areas and interacting with them in those environments has been shown to be clearly associated with the development of many illnesses with which humanity is plagued.
How Human And Plant Behavior Affect Each Other
In the summer of 2010, Dr. Robert Svoboda and I were invited by Erick Schulz and Dr. Aderson Moreira da Rocha, to teach about 50 participants for about a week, in a rural center about an hour outside of Sao Paulo, Brazil. It was a committed group of students and the event went smoothly. It culminated, on the final evening—the evening preceding the new moon—with the company of Dona Francisca, a shaman and medicine woman from the Yawanawa (pronounced, “shawah nawah”) tribe, a two-day boat ride up the Amazon. Mother to eleven of her own children, she has delivered between one and two thousand babies. She delivered her first when she was 15 years old, after apprenticing since the age of seven or eight.
Among other things, Dona Francisca talked about the importance of how we collect herbs for healing purposes. Se said that, not unlike humans, plants feel pain. That, as we would not relish someone pulling our hair, scratching our bodies or subjecting us to harsh treatment, the plants also do not enjoy rough treatment. That, if we collect plants in a violent, thoughtless manner, without asking their permission and praying, that those plants will cause disease in us, our patients, and to the planet.
With the increasing popularity of complementary forms of medicine, like Ayurveda, we are turning from pharmaceutical medicine to plant medicine to address our ills. In our enthusiasm for new remedies or knowledge, we may be overlooking some subtle but important details. And, in so doing, may be depleting supplies and the quality of the very herbs upon which we rely, and are ignoring direction our own texts have provided us.
Caraka details appropriate collection methods in the first chapter of Kalpasthāna. Along with the more obviously practical method of plant collection, like appropriate time and season, he says,
One should collect the various parts of these plants while facing towards the east or north after performing auspicious rites in a spirit of compassion, while living a pure life, while wearing white dress, after offering prayers to the gods, Asvins, cows and Brahmins, and while observing fast.
The collected plant products should be kept in appropriate containers, well-covered with a lid, and hung on a swing. The storeroom should have doors facing towards the east or the north. …Flower offerings and sacrificial rituals should be performed in the storeroom every day… [i]
This is a humbling passage, when we consider how our plants are often grown, harvested, stored, distributed, prescribed and consumed in the modern day. Though it may seem daunting for physicians to follow Caraka’s counsel, he is also clear that, while it is ideal for physicians to recognize and harvest their own herbs, it is not essential. This part can be done by goatherds, shepherds, cowherds and other forest dwellers.[ii] In the modern world, this can be done by gardeners and overseen by companies that take it upon themselves to grow organic herbs in a sustainable and respectful manner that follows the spirit of the texts as much as possible.
Modern complementary medicine systems, like Ayurveda, are frequently hailed as being holistic and compassionate, but if we use Caraka’s direction as a yardstick by which to measure our practices, we may find room for improvement.
How we treat plants and animals affects their qualities. As a framework within which to explore this, it is useful to consider the qualities that Caraka[iii] informs us are essential for a substance to possess in order to be efficacious.
Abundance, suitability, multiple form and potency; these are the four qualities of medicament.[iv]
As it happens, each of these qualities in plants and animals, are related to each other and to our relationship with them. Each quality depends, in part, on how we treat the plant or animal, how we treat each other, and how we treat our planet.
The first among the qualities Caraka lists as criteria for effective medicinal substance, is abundance. The plant medicine we give to our patience should be abundant.
In 2010, in South India, a vaidya told me that 120 Ayurvedic herbs—many, like bilva, that are commonly used—were now on the restricted or endangered list there. (The opposite of abundant.) When I asked what the community was doing to address this, he told me they were finding substitute herbs. While this approach may conform to Caraka’s dictum to the letter, it may be prudent to consider why the herbs are becoming scarce to begin with. After all, what happens when the substitute herbs are used to the extent that they too become endangered? And, if we continue using herbs in the manner that drove the first to scarcity, the same will happen to the substitutes.
The book Collapse (Collapse: How Societies Choose to Fail or Succeed by Jared Diamond) describes how certain cultures or communities over millennia became extinct. Each community that suffered this fate exploited its natural local resources, without finding ways to replenish them as they went along. Eventually they cut down the last tree, polluted the last water source or harvested the last essential resource. And then. There was nothing left. Not only did their resources perish, but they themselves perished.
We have already seen kutki, jatamamsi, chandana, and other precious plants become endangered. More and more– even very common– Ayurvedic herbs are being added to the “endangered” list every year and we continue to support the practices that lead to this situation.
Most of us who practice Ayurveda are aware that abundance is currently threatened, but it is worth considering how the other three qualities relate to abundance.
The question of whether any given substance is appropriate for a patient, is related to the question of abundance.
First we overuse and misuse (atiyoga andmithyayoga) nature’s bounty by overeating in general, or consuming food and drink that has been grown in mono-cultures or unnaturally packed environments (as may be the case with many swine or fowl, “farms”, adulterated with chemicals and by excessive processing. This makes us sick and then we go back to Nature’s cupboards to find yet more substances to help us, when we could simply stop the practices that led to disorders in the first place. The more suitable medicine would be changes to lifestyle, diet and how we grow our food.
If remedies beyond diet and lifestyle are deemed necessary, as physicians, we might do well to consider what Caraka says are the qualities of a patient that lead to successful treatment,Good memory, obedience, fearlessness and uninhibited expression—these are the four qualities of a patient.[v] It is up to us to determine, as best we can, whether a patient is likely to be obedient enough to take the substances we prescribe. If they are not likely, then again, it would be more prudent to simply offer lifestyle and dietary recommendations, and save the remedies for patients who will actually take them. Otherwise, the patient purchases the substances, may take a dose or two, and then puts them in the back of a drawer to lie in waste. This was a plant or animal that might otherwise have been used to ease another’s suffering, or even simply left to grow and contribute to whatever ecosystem in which it had been participating.
Caraka tells us that there is nothing in the world that is not therapeutic in appropriate conditions and situations[vi] so we should be able to find something that is abundant that the patient will actually take or do that will not be depleting the earth of some of her more rare treasures. This will not only be more suitable for our patients, but also for the plants or animals.
In the Dravyagunavignyana, it is said that Vagbhatta[vii], was usually inclined to use single herb remedies, as he recommended the use of a single herb or remedy in 42 of 55 cases.[viii] While certain cases may require formulations of multiple herbs, perhaps we should not overlook the possibility that one herb, if cultivated, harvested and prescribed with love and respect, could be sufficient to address disorder in the strotamsi, dosas or dhatus. Why use multiple plants when one is suitable? And, why use one, when a malady may be addressed solely though changes in lifestyle and diet.
As of 1993, it was estimated that there were about 250,000 species of plants, only some 5000 that had been studied to any extent in western science. At that time only 95 of those species were the basis of the 120 plant-based prescription drugs.[ix] The medicinal potential of species in many parts of the world has only begun to be tapped, but we may never have the opportunity to realize this potential.
It has been estimated that by the year 2000, some 10 % of the species of plants on our earth became extinct.[x] One hundred years ago the human population stood at about one billion. Now we are well over 6 billion. The rate at which we are using Mother Nature’s resources is increasing exponentially. Some experts, for example, believe that rain forests are shrinking by about one hundred acres per minute.
Not only is the diversity of our plants disappearing, but the guardians and stewards who know them best are disappearing as well. Decades ago, Harvard professor and explorer of the Amazon, Richard Evans Schultes, said that over 90 Brazilian tribes had become extinct since the turn of the twentieth century.[xi] These were tribes and people who had intimate and vast knowledge of plants and, with their disappearance we have doubtless already suffered an incalculable loss.
We are living in world that currently favors monocultures over diversity. With the use of toxic chemicals, insecticides, fungicides, and pesticides, we are able to grow huge mono-crops of corn, soy and other increasingly distorted crops. When we change the environment in which a plant grows, we also change how it grows. This is not limited to adulterated crops like corn and soy. This occurs in common plants as well.
Science Daily recently reported, for example, kin recognition in Impatiens pallida (yellow jewelweed) and how that affected the way they grew.[xii] When they grew next to unrelated plants, in areas where sunlight and nutrients were precious commodities, they would allocate their resources to their leaves and roots, so the leaves would grow large and crowd out other species, and their roots would spread more quickly and widely, to effectively capture available nutrients. They became the strongest plants they could be. When one plant grows strong, other species in the environment are forced to find their own niches in any given ecosystem, where they too can flourish. In order to survive, each species is forced to develop unique strategies. The plants’ qualities and potency will reflect these strategies.
Something different happens in monocultures. When that same Impatiens grows next to relatives, they grow smaller leaves and meeker root systems, so as to share resources with their kin. While this in itself may not be a problem in certain ecosystems, it could become a problem if we take herbs that naturally grow in an environment of diversity and we grow them as mono crops. As with the Impatiens, this practice may result in weaker plants in other species as well.
This is worth considering when we attempt to grow medicinal (or other) plants that have historically been wild-crafted in diverse habitats, in mono crops. It is likely that we are altering their qualities and thereby the effects they will have on us.
Multiple forms of plants are the basis for countless medicines and their inherent qualities. As monocultures are replacing diversity at a rate previously unknown, it is not superstition to fear that the diversity of our medicinal plants is in danger, and the qualities we have historically associated with certain medicines are changing in response.
Potency (vīrya) may be the most intriguing of the four qualities of effective medicine. In a largely under-explored relationship, how we collect plants for medicinal purposes, as well as for common dietary purposes, almost certainly directly their potency. Caraka says,
It is not that the various drugs and diets act only by virtue of their qualities. In fact, they act by virtue of their own nature or qualities or both on a proper occasion, in a given location, in appropriate conditions and situations; the effect so produced is considered to be their action (karma); the factor responsible for the manifestation of the effect is known as vīrya; where they act is the adhisthāna; when they act is the time, how they act is the upāya or mode of action; what they accomplish is the achievement.[xiii]
There are various factors that determine a plant’s cumulative effect on a patient. A plant’s rasa, vīrya, vipāka, prabhāva, guṇas, and karma —taste, potency, after effects, special effects, qualities and actions respectively—are affected by how it is treated and by the nature of its environs.
We know that a plant feels pain and even responds to intent, from the work of scientists like the famous biologist, Dr. Jagadish Chandra Bose. Dr. Bose began experimenting on plants in 1900 and found them to have sensitive nervous systems that responded to spasms just as animals’ muscles. He found they grew more quickly when exposed to sweet music and their growth was slowed and thwarted when exposed to loud or harsh sounds.[xiv]
In the 1960s, former CIA interrogation specialist Cleve Backster, inspired by Bose’s work, connected polygraph sensors to plants and found that not only did they respond to having their leaves cut, but even to human’s harmful thoughts towards them. He also found plants were aware of each other and mourned the death of any of them. When boiling water was poured down a drain, the plants even mourned the resulting death of bacteria. They “strongly disliked people who killed plants carelessly or even during scientific research, and fondly remembered and extended their energy out to the people who had grown and tended them, even when their ‘friends’ were far away in both time and space.”[xv] The plants would react instantaneously to events occurring thousands of miles away and could anticipate both positive and negative events.[xvi]
For our purposes, it is also interesting to note that plants responded to overwhelming danger by becoming catatonic and “checking out.” Sometimes this phenomenon is dramatically visible. Consider the foliage of the Sensitive Plant (Mimosa pudica), which actually collapses, playing dead, when disturbed, and returns to normal once the danger has passed. If we rip a plant out of the ground at a time when it has voluntarily suspended its vitality and has “checked out” or is playing dead, we have to at least wonder if this suspends the plant’s potency, altering its guṇas and reducing its efficacy.
There are many examples of plants responding to threats or stimuli, like the famous Venus flycatcher –who’s electrical response is almost identical to nerve impulses in animals. Indeed, a plant responds not only to threats to its own well being, but to plants around them, sometimes sacrificing their own vitality for the good of the community. The Impatiens that we looked at above, for example, sacrifices some of its own vitality for the well being of its kin.
There are at least several ways plants have been shown to communicate with each other. The Impatiens recognized their kin by a kind of communication transmitted between their roots. Acacia trees communicate through the air. They produce tannin when they are confronted with threats, like grazing. The scent of tannin is airborne and transported to other acacia trees, which respond by producing tannin of their own, to fend off similar danger in the neighborhood. How plants respond to perceived danger can change their composition and even the composition of their neighbors.
Some plants respond to danger by secreting chemicals to attract certain kinds of insects that attack their aggressors. One type of orchid, for example, secretes a chemical identical to one that a certain bee produces. This kind of bee happens to be a food source for a certain kind of hornet, who habitually feeds them to their hornet young. When the hornets smell the bee’s scent emitting from the orchid, they pounce on it, unwittingly serving as pollinators. Other clever orchids –that have no sugar of their own–tempt pollinators by secreting scents of flowers that actually deliver nectar.
Species conspire, consciously or otherwise, to survive, and the chemistry of species reflects this conspiracy. This applies not only to species among themselves, but to interspecies communication. For example, there is a certain fungus that lives symbiotically with leaf-cutting ants (Atta sexdens rubropilosa), which feed it plant matter. When they feed the fungus some plant matter that is toxic to it, the fungus signals the danger to the worker ants that, in turn, avoid fertilizing the fungus garden with that plant thereafter.
In recent news, the prestigious journal, Plant Physiology, recently reported that Michigan State University researchers confirmed that plants have rudimentary nervous systems that allows them to feel pain. Plants are able to identify danger, communicate that danger to other plants, and rally defenses against it. While this news may seem a bit redundant in the face of work like Bose, it was such convincing research that it was a factor in the Swiss government passing a Plant Bill of Rights, the first ever of its kind that legislates moral and legal protection and appropriate treatment for plants.
He alone is a good physician who knows the specific nature of rasas, dravyas, doṣa and diseases, as well as habitat, time and physical constitution.[xix]
What does this all have to do with us? If we are violent to plants or animals, they may alter their rasa, vīrya, vipāka, prabhāva, guṇa, and karma—their chemistry—in an attempt to protect themselves. This may initiate a chain reaction, altering kindred plants, animals and their environment. If humans are consistently the threat, is it not likely that substances will evolve to be toxic to their antagonists? Indeed, if we accept the theory of evolution, such an outcome would be inevitable, over time. Substances, in an evolutionary effort to survive, will adjust their guṇas to be less hospitable, or even poisonous to humans. We could not then expect the substances to continue to possess the guṇas, vīryas and karmas they possessed in the past.
This ability for the qualities of substances to change over the ages was not ignored by the sages (ṛṣis). For example, they tell us how the qualities of food grains—that is, seeds—have changed over yugas (ages), depending on prevailing conditions and environments:
In the beginning of the satyuga [the first age] [xvii], because of the noble mind, qualities and actions of the people, the earth, etc. got endowed with all the good qualities, as a result of which excellent rasa, vīrya, vipāka, and prabhāva were manifested in food grains.
At the end of the satyuga, some rich people got heaviness in their bodies due to over-indulgence. They suffered from fatigue because of the heaviness of the body. Fatigue gave rise to laziness; laziness caused them to accumulate things; accumulation led to the attachment for these things and attachment resulted in greed.
During tretayuga [the second age], greed gave rise to malice; malice gave rise to false statements and from false statements arose passion, anger, vanity, dislikes, cruelty, infliction of injury, fear, sorrow, grief, worry, anxiety, etc. Therefore, during tretayuga, a quarter of dharma disappeared. Because of this, the life span of human beings was reduced by a quarter. Similarly, there was reduction in the attributes of earth, etc., by one quarter. Because of the reduction of these attributes there was diminution by one quarter of the unctuousness, purity, rasa, vīrya, vipāka, prabhāva and guṇas of grains.
Because of the reduction by a quarter of the attributes of diets and regimens, there was an unusual change in the maintenance of equilibrium of tissue elements and there was vitiation of agni and maruta (wind) by which, first of all, bodies of living beings got afflicted with diseases, vis. jvara, etc. Therefore the lifespan of living beings underwent gradual diminution. 24
Thus it is said, dharma and qualities of living beings got reduced in quarters gradually by the passage of each [of the four] yuga 25….[xviii]
In summary, the potency of all plants reduced by roughly a quarter with each of the four ages. Considering that we are considered to be living in the forth stage, we have already lost more than three quarters of the original potency of plants. The qualities and potency of plants respond to the level of violence or peace experienced at the time of fertilization, growing and collection. Plants are imbued with the guṇas they develop in response to their environment, and have no choice but to yield these guṇas into those who consume them. The more violent or disrespectful our behavior towards plants, the more they develop qualities toxic to humans. The more toxic material we consume, the more diseased our bodies and intellects become. The more distorted our intellect, the more likely we are to fall prey to lust, anger, greed, attachment and egoism and to therefore treat plants with ignorant disregard. It is a vicious cycle.
Ancient texts of Ayurveda foretold times would come that, because of the aberrations of taste (rasa), potency (vīrya), after effects (vipāka), special effects (prabhāva) and qualities (guṇas) as described above, would foster abnormalities that would inevitably lead to epidemics. While this article is focusing on plants, these premises may–probably must–apply as well to animals, as both animal and plant medicine was used in Ayurveda and included in the term, “drugs” (dravya). Indeed, many contagious diseases arise from the perhaps unnaturally close contact between humans, fowl and swine. (Hence, “swine flu” and, “avian or bird flu”). Lord Atreya tells Agnivesa that, since the beginning of creation, sinful acts have preceded periods of difficulty.[xx] He describes,
O Agnivesa! some abnormalities are now appearing in the stars, planets, moon, sun, air, fire and diks (directions). This forecasts abnormality in the coming seasons. Very soon, the earth will cease to manifest proper rasa, vīrya, vipāka, and prabhāva in drugs. This is bound to result in the widespread manifestation of diseases. Therefore, O Agnivesa, all of you should collect drugs before the time of destruction and before the earth loses its fertility leading to the impairment of the rasa, vīrya, vipāka and prabhāva of drugs grown over it. We shall administer these drugs having correct rasa, vīrya, vipāka and prabhāva to such of our patients as are dependent upon us and whom we desire to treat (because of the curability of their ailments). It is not difficult to treat epidemic diseases, provided the drugs are collected, preserved and administered properly. 4[xxi]
Caraka seems to be talking specifically about an epidemic and, if we read on, we can see how epidemic is defined.
Factors responsible for epidemics:
Lord Atreya replied, “Agnivesa,” even though there is dissimilarity in the physical constitution of human beings, still there are such factors as are common to all individuals and vitiation of these factors leads to the simultaneous manifestation of diseases having the same set of symptoms leading to the destruction of countries. Factors which are common for all the inhabitants of a country are air, water, location and seasons. 6[xxii]
One need only have average awareness to be aware that our air, water, land and seasons are all currently disturbed and that modern day epidemics like cancer, heart disease, diabetes, auto immune disorders and other calamities are disturbing and claiming lives in staggering numbers. To consider that the plants, animals and herbs we are consuming as food and medicine, are immune to the polluted and disturbed air, water, location and seasons, would be irrational. Along with these disturbed elements, they are affected by the actions of the very humans that depend on them.
Lord Atreya said that the cause of such epidemics is the sins of present and past lives, rulers that are misguiding people and people who are abandoning righteous behavior. In such places, the seasons, rainfall, winds and earth become disturbed and, “drugs lose their normal attributes and get impaired. Then there is impairment of the country because of the impairment of food and drinks.”[xxiii] It is therefore incumbent upon us to grow and harvest our medicinal substances according to the practices enjoined on us by our founding texts.
While it may seem hopeless to be able to avoid the effects of the modern day imbalances, there is always hope. Even during an epidemic, Lord Atreya says, there are ways to stay healthy.
Truthfulness, compassion for living beings, charity, sacrifices, prayer to the gods, adoption of preventative measures, tranquility, protection of the self by mantra, etc., search for things that are good for the self, residence in auspicious places, observance of brahmacaryā, service to those observing brahmacaryā, discussion of religious scriptures, great sages and those who have self-control, and constant association with religious, sāttvika and learned persons—these are the therapies which if adopted during the epidemics can easily save the lives of individuals provided the death of a particular individual during the period is not predestined.12-18[xxiv]
Note that herbal or animal remedies are not anywhere in this list of therapies that work during an epidemic. It is largely asking us, as my Guruji advised me when I was eight years old to, “keep good company”, as well as to cultivate our own qualities such that we become good company.
It is not that remedial substances are never required, but if we commit to the behavior Lord Atreya counsels, we have no choice to treat our plants and animals better, and use them more judiciously. In turn, they will serve us better. If we all—food and herb growers, harvesters, sellers, prescribers and consumers—were to engage in this respectful process, perhaps our plants and animals would be more potent and we would require fewer of them and smaller doses, to achieve equal or better results.
It is not uncommon for students and practitioners of Ayurveda to hail the success of spreading Ayurveda around the globe, and beam at this accomplishment. But it may prove a Pyrrhic victory if we do not also import and export the respect of the substances upon which we rely.
We stand at a unique time in evolution. We find substantial, fantastic and fantastical advances in technology. Concurrently, we have access to the wisdom of ancient texts, like the Three Greats– bṛhat trayī, and to tribes like those in the Amazon that, to date, have had minimal or zero contact with inhabitants of the “modern world.” These are texts, tribes and communities that continue to have a relationship with nature—one that has continued without pause, for many thousands of years. Their knowledge of plants, animals, healing, and cultivating a sustainable relationship with our environments are the product of thousands of years of observation and wisdom acquired from physical or divine experimentation or revelation.
South American tribes and traditions like Dona Francisca’s still have a very strong, vibrant, active relationship with physical and spiritual manifestations of nature and her plants. How long yet will we have access to such precious resources? Who can say. If we miss this opportunity, we are unlikely to find it readily elsewhere. Inshallah, their wisdom will nourish, inspire and educate the rest of us before we have cut down the last tree, consumed our last teaspoon of triphala, or let our last bag of herbs mildew in our closets.
Much of this information was further researched, refined, edited and adapted to Part VI of Dr. Claudia Welch’s book, The Four Qualities of Effective Physicians.
For a more in-depth look at rasa, vīrya, vipāka, prabhāva and guṇas, including a discussion vīrya that many serious students of Ayurveda may find quite interesting, you might consider taking the following stand-alone online lessons, from our complete online courses Foundations of Ayurveda Parts I & II:
Foundations of Āyurveda Part I, Lesson 4 – Tridoṣic Theory: The 3 Doṣas & The 6 Tastes
Foundations of Āyurveda Part II, Lesson 6 – Dravya, Karma, Vipāka, Prabhāva & Review of Rasa and Vīrya
[i]Caraka Saṃhitā: kalpasthāna:I:10-11. Suśruta says the gatherer should look towards the north at the time of harvesting, and that plants should be regarded as partaking in the virtues of the ground they grow on. Suśruta Saṃhitā: Sūtrasthāna :xxxvii:2 Other than these passages, I have not found other passages in the bṛhat trayī that relate to the attitude one should cultivate while harvesting. This may be because it was taken as a given that practitioners would treat plants this way. Just as it is unnecessary to counsel practitioners not to hit their patients, it may have been assumed that practitioners would consider the well being of the plant medicine upon which they depended.
[ii] Caraka Saṃhitā: Sūtrasthāna: i:120-123
[iii] Caraka is the author of Caraka Saṃhitā, one of the fundamental Ayurvedic texts
[iv] Caraka Saṃhitā: Sūtrasthāna:7
[v] Caraka Saṃhitā: Sūtrasthāna:ix:9
[vi] Caraka Saṃhitā: Sūtrasthāna:xxvi:12
[vii] author of Aṣṭāṅga Hṛdayam, a fundamental Ayurvedic text
[viii] dravyagunavignyana;pt I;p 35, vaidya v.m. Gogte. general editor S. Ramakrishnan. bharatiya vidya bhavan. Mumbai. 2000.
[ix] Mark J. Plotkin, Ph.D, Tales of a Shaman’s Apprentice, An Ethnobotanist Searches for New Medicines in the Amazon Rain Forest, 1993. P.7
[x] Mark J. Plotkin, Ph.D, Tales of a Shaman’s Apprentice, An Ethnobotanist Searches for New Medicines in the Amazon Rain Forest, 1993. P.13
[xi] Mark J. Plotkin, Ph.D, Tales of a Shaman’s Apprentice, An Ethnobotanist Searches for New Medicines in the Amazon Rain Forest, 1993. P.13
[xii] Can a Plant Be Altruistic?, ScienceDaily (Nov. 12, 2009)http://www.sciencedaily.com/releases/2009/11/091111092047.htm
[xiii] Caraka Saṃhitā: Sūtrasthāna:xxvi:13
[xiv] http://en.wikipedia.org/wiki/Plant_perception (paranormal)
[xvi] Backster first published his findings from these experiments in the International Journal of Parapsychology
[xvii] Satya Yuga, the age of truth; the golden age of mankind. After Satya Yuga come three, progressively more morally poor and physically weaker ages: Treta Yuga or Silver Age, Dvapara Yuga or Bronze Age and the present yuga, Kali Yuga or the Iron Age.
[xviii] Caraka Saṃhitā:Vimānasthāna:III:24-25
[xix] Caraka Saṃhitā:Vimānasthāna:I:26
[xx] Caraka Saṃhitā:Vimānasthāna:III:24
[xxi] Caraka Saṃhitā:Vimānasthāna:III:4-8
[xxii] Caraka Saṃhitā:Vimānasthāna:III:4-8
[xxiii] Caraka Saṃhitā:Vimānasthāna:III:19-20
[xxiv] Caraka Saṃhitā:Vimānasthāna:III: 12-18