Part 11 - The Theory of Rasas and their Chemistry

The theory of Rasas or tastes plays an important part in Āyurveda in the selection of medicines and diet and in diagnosing diseases and arranging their cures. In 1. 26 of Caraka we hear of a great meeting of sages in the Caitraratha Forest, attended by Ātreya, Bhadrakāpya, Śākunteya, Pūrṇākṣa Maudgalya, Hiraṇyākṣa Kauśika, Kumāraśiras Bharadvāja, Vāryovida, the Vaideha king Nimi, Badiśa and Kāṅkāyana, the physician of Balkh, for the purpose of discussing questions of food and tastes.

Bhadrakāpya held that taste, or rasa , was that which could be perceived by the organ of the tongue and it was one, viz. that of water. Śākunteya held that there were two rasas, nutritive (upa-śamanlya) and denutritive (chedanīya).

Pūrṇākṣa held that there were three rasas,

1. upaśamanīya,
2. chedanīya
3. and neutral (sādhāraṇa).

Hiraṇyākṣa held that there were four rasas, sweet and good, sweet and harmful, distasteful and good, distasteful and harmful.

Kumāraśiras held that there were five rasas,

1. earthy,
2. watery,
3. fiery,
4. airy
5. and ethereal (āntarikṣa).

Vāryovida held that there were six rasas,

1. heavy (guru),
2. light (laghu),
3. cold (śīta),
4. hot (uṣṇa),
5. smooth (snigdha)
6. and dry (rūkṣa).

Nimi held that there were seven rasas,

1. sweet (madhura),
2. sour (amla),
3. salt (lavaṇa),
4. hot (katu),
5. bitter (tikta),
6. pungent (kaṣāya)
7. and alkaline (kṣāra).

Badiśa added one more to these, viz. unmanifested (avyakta), and held that there were eight rasas.

Kāṅkāyana held that the rasas were of infinite variety and could not be counted, on account of the diversity of

• substances in which they are located (āśraya),
• their specific properties as light or heavy (guṇa),
• their action in developing or reducing the constituents of the body (karma)
• and their diversity as apparent to the organ of taste.

Ātreya Punarvasu held that there are six rasas only,

1. sweet (madhura),
2. acid {amid),
3. saline (lavaṇa),
4. hot and pungent (kaṭu),
5. bitter (tikta)
6. and astringent (kaṣāya).

The source (yoni) of all these rasas is water. Its actions are sedative (upaśamana) and denutritive (chedana), and a basis of equilibrium (sādhāraṇatva) of the rasas is reached when those having the above opposite actions are mixed together. Pleasantness (svādu) or unpleasantness (asvādu) of taste depends on liking or disliking.

The seats of rasas are the essences of the five elements (pañca-mahā-bhūta-vikārāḥ) modified in accordance with five conditions, viz.

1. specific nature of the substance (prakṛti );
2. as acted upon by heat or other agents (vikṛti);
3. association with other things (vicāra);
4. the place in which the substance is grown (deśa);
5. the time at which it is produced (kāla)^[1].

The guṇas of heaviness, lightness, cold, warm, moisture and dryness belong to the things to which the rasas belong. The alkaline (kṣāra) should not be counted as a separate rasa, as it is made up of more than one rasa and affects more than one sense-organ; for it has at least two important rasas (of “hot and pungent” and “saline”) and it affects not only the organ of taste, but also that of touch, and does not naturally belong to any substance, but has to be created by artificial processes. There is no such separate rasa which can be called unmanifested (avyakta).

Water is the origin of all rasas ; so all rasas may be considered as existing in an unmanifested state in water, but that is no reason why we should say that water has a separate taste called “unmanifested”; moreover, when a substance has two rasas, one dominant and the other extremely feeble, the feeble rasa may be regarded as unmanifested; or, when in a compound of different rasas, say, of a syrup, a slight hot taste is added, this may be considered as unmanifested; but certainly there is no rasa to which the name “unmanifested” (avyakta) could be given. The view that there is an infinite number of rasas is untenable; for, though it may be urged that the same rasa may occur differently in different objects, that would only go to show that there are various grades of forms of each particular rasa and not prove that with each variety of a particular rasa the rasa itself is wholly different. Again, if different rasas are mixed together, the mixed rasa itself is not entitled to be counted as a separate rasa ; for its qualities are just as the sum total of the qualities of the different rasas which are its constituents, and no independent work can be attributed to this mixed rasa (na saṃsṛṣṭānāṃ rasānāṃ karmopadiśanti buddhimantaḥ), as in the case of a compound of two or more substances, as mentioned above (vicāra).

Though on account of the predominance of one or the other of them they are called earthy (pārtkiva), watery (āpya), fiery (āgneya), airy (vāyavya) or ethereal (ākāśātmaka), yet all substances are compounded of the five elements. All substances, whether animate or inanimate, are to be considered as medicines (auṣadha), provided they are applied in the proper way (yukti) and for specific purposes (artha). A substance can be a medicine only when it is applied in the proper way and for specific purposes; nothing can unconditionally be considered a medicine. The medicative influence is exerted both by virtue of the specific agency of a substance (dravya-prabhāva) and by the specific agency of its qualities, as also by their joint influence^[2]. The action of medicines is called karman , its potency vīrya , the place where they operate adhi-karaṇa , the time of operation kāla, the mode of operation upāya, and the result achieved phala.

As regards the origin of rasas , it is suggested that water gets mixed with the five elements in the air and also after its fall on the ground. These rasas nourish the bodies of all plants and animals. All the five elements are present in all rasas ; but in some rasas some of the elements predominate, and in accordance with this there are differences among the various rasas. Thus, with the predominance of soma there is a sweet taste, with the predominance of earth and fire an acid taste, with water and fire a saline taste, with air and fire, hot and pungent, with air and ākāśa , bitter, with air and earth, astringent. The different elements which take part in the formation of rasas are said to be instrumental causes (nimitta-kāraṇa) of the rasas ; this explains how, though fire has no rasa , yet it may help the generation of a particular rasa^[3]. Destiny or unknown cause (adrṣṭa) is, however, the general cause of such combinations of elements with water.

In the very first chapter of the Caraka-saṃhitā , substances (dravya) are counted as being the five elements, viz.

1. ākāśa,
2. air,
3. light,
4. heat,
5. water
6. and earth,

together with

1. soul,
2. manas,
3. time

and space.

Of these those substances which possess sense-organs are called animate and those which do not are called inanimate^[4].

The guṇas are the sense-properties of

• hearing,
• touch,
• colour,
• taste
• and smell,

the mechanical and other properties which all elements have in common, such as

• heaviness,
• lightness,
• cold,
• heat, and moisture,
• dryness,
• dullness,
• sharpness,
• steadiness,
• mobility,
• softness,
• hardness,
• motion,
• slipperiness,
• smoothness,
• roughness,
• grossness,
• fineness,
• thickness,
• liquidity, etc.,
• and desire,
• hatred,
• pleasure,
• pain and effort,
• intelligence (including memory),
• consciousness,
• patience,
• egoism, etc.,
• distance (para),
• nearness (apara),
• combination (yukti),
• number,
• contact,
• disjunction (vibhāga),
• separateness,
• measure,
• inertia (saṃskāra)
• and repetition (abhyāsa).

The definition of substance (dravya) is, that which possesses quality (guṇa) and action (karma) in the relation of inherence and is also the inseparable material cause (samavāyi-kāraṇa) of all effects. Guṇas are things which are themselves inactive and exist in dravyas in an inseparable relation of inherence. The guṇas themselves cannot contain any further guṇas^[5].

The above being the theory of dravya and guṇa , the question arises as to the way in which medicines operate in human bodies. The most general and obvious way in which the different medicines were classified was by their different tastes, which were considered primarily to be six in number, as has already been pointed out. Each of the tastes was considered as being capable of producing certain good or bad physiological effects. Thus the sweet taste is said to increase blood, flesh, fat, marrow, semen, life, to do good to the six senses, and to produce strength and colour of the body; to do good to the skin and throat, to destroy pitta , poison and māruta (morbidity of air), and to produce moistening, cold and heaviness, etc.

The acid (amla) is said to rouse digestion, develop the body, and to remove vāta ; it is light, warm, moist, etc. The saline taste is digestive; it removes vāta, secretes kapha ; and it is moist, warm, etc. And so on with the other tastes. But, of course, all these qualities cannot belong to the tastes; as has already been pointed out, the guṇas cannot possess further guṇas , and the tastes (rasa) are themselves guṇas ; so, when certain functions or properties are attributed to the rasas , they must be considered as belonging to the substances which possess those specific rasas (rasa iti rasa-yuktāni dravyāṇi)^[6].

From Suśruta’s statements it appears that there was a great difference of opinion regarding the relative prominence of dravya and its properties^[7]. There were some who held that dravya was the most important, since dravya remained permanent, whereas rasa, etc. are always changed; so dravya is relatively permanent. Again, dravya is grasped by the five senses, and not its guṇas. The dravya is also the support of the rasas, etc. All operations have to be done with the dravya, and the authoritative texts also speak of operations with the dravyas , and not with the rasas ; the rasas depend largely on the nature of the dravyas. Others hold that rasas are the most important, since it is of them that we become directly aware when we take our food, and it is said that they remove the various morbidities of vāta, etc. Others hold that the potency (vīrya) of things is the most important, since it is by their potency that medicines act^[8].

This potency is of two kinds,

1. hot (uṣṇa)
2. and cold (śīta);

some think that it is of eight kinds,

1. hot (uṣṇa),
2. cold (śīta),
3. moist (snigdha),
4. dry (rūkṣa),
5. moving (viśada),
6. slippery (picchila),
7. soft (mṛdu)
8. and sharp (tīkṣṇa).

Sometimes potency or vīrya overcomes rasa by its power and makes its own tendencies felt; thus, though sugar-cane ought to remove vāta on account of its sweetness, it really increases it on account of its being śīta-vīrya (of cold potency)^[9]. Others say that the rasa, as digested by the stomach (pāka), is most important, since things can produce good or bad effects only when they are digested. Some hold that each rasa remains unchanged by digestion, though according to others there are only three kinds of rasa resulting from digestion or pāka , viz. sweet, acid and hot (katu); whereas Suśruta held that there were only two kinds of rasa resulting from digestion, viz. sweet and hot; for, in his view, acid was not the result of digestion (amlo vipāko nāsti). According to Suśruta it is the pitta which is turned into acid. Those objects which have more of earth and water in them are turned into sweet taste, whereas those which have tejas, air and ākāśa as their ingredients are turned into hot taste (katu).

Speaking of the differences of view regarding the relative importance of dravya, rasa , vīrya and vipāka , Suśruta says that they are all important, since a medicine produces effects in all those four ways according to its own nature^[10]. The view of Suśruta, as explained by Cakrapāṇi in the Bhānumatī, seems to be that food, drink and medicine are all products of the five mahābhūtas, and rasa, vīrya and vipāka are dependent on the dravya and are like its potency (śakti), through which it works^[11]. Cakrapāṇi, commenting on this in the Bhānumatī, says that even in those cases where certain rasas are said to remove or increase certain morbidities (doṣa) it is only because of their importance that they are so described; the real agent in all such cases is the dravya, since the rasa, etc. are always dependent on the dravya. Apart from the śakti as manifested in rasa, etc., the dravya also operates by itself in an unthinkable way (acintya), which is also called prabhāva and which is comparable with the attractive force exerted by magnets on iron.

The dravya by itself is thus differentiated from its śakti, and it is said to have a peculiar operative mode of its own, as distinguished from that of its śakti or potency, as manifested in rasa, vīrya or vipāka , and this mode of operation is considered to be quite unthinkable (acintya) as to the way in which it operates^[12]. Thus some medicines operate by rasa, some by vipāka, or the rasa resulting from the digestive operation (e.g. śuṇthl, which, though hot in taste and hot in vīrya, is sweet after digestive operation), some by vlrya (e.g. kulattha, though pungent, yet removes vāyu on account of its hot vīrya), some by both rasa and vipāka, some by dr avya-pr abhāva, vīrya and rasa, some by dravya-prabhāva, vīrya , rasa and vipāka.

Caraka, however, differs from Suśruta in this view of drayva and rasa, vīrya and vipāka ; for, according to him, rasa, vīrya and vipāka, themselves being guṇas, cannot possess further guṇas. He does not admit a śakti as different from the dravya. Thus in the case of prabhāva, while Suśruta holds that it is a specific śakti, or the thing operating in unaccountable ways, Caraka thinks that this śakti is identical with the thing itself.

Thus Cakrapāṇi in explaining Caraka-saṃhitā , 1.26.72, says,

“śaktir hi svarūpam eva bhāvānāṃ, nātiriktaṃ kincid dharmāntaraṃ bhāvānām”

(potency is the nature of things and is no separate property distinct from them).

Vīrya in its general sense means “the potency or power of medicines to produce effects,” and as such includes within it both rasa and vipāka; but, since these have special names, the term vīrya is not applied to them^[13]. Apart from this there is special vīrya in a technical sense (pāribhāṣika). In the view which considers this vīrya to be of two kinds, snigdha and rūkṣa, these are to be taken as specific characteristics; but in the view which considers the vīrya to be of eight kinds, these are to be taken as a different set of characteristics of dravya or substance^[14]. This vīrya is believed to be more powerful than rasa , so that, when the vīrya and rasa of a thing come into conflict, it is the vīrya which predominates and not the rasa.

Vāgbhata junior makes some remarks in support of the name vīrya , as given to the characteristics which go by that name. He says that, since the vlrya characteristics of things remain unchanged even after digestion, and since the things are primarily in use for medical purposes and each of them would include many substances and rasas, this character justly deserves to be called vīrya, or the potency-in-chief for producing medical effects^[15]. He further says that rasa is baffled by vipāka, that rasa and vipāka can baffle vīrya, if they work in the same direction, and that they may all be baffled by prabhāva. These remarks, however, are true only in those cases where rasa, vīrya and vipāka exist in the same proportion, and it must be borne in mind that some objects may have rasa of such a predominant type that it may overcome the vipāka or the vīrya^[16]. As regards the relative priority of vīrya and vipāka, Śivadāsa in commenting on Cakrapāṇi’s Dravya-guṇa-saṃgraha says that vīrya is prior to vipāka; and this would imply that, as vīrya can supersede rasa, so vipāka may supersede vīrya.

If we look back to the earliest history of the development of Indian medical ideas in the Atharva-Veda, we see that there were two important classes of medicines, viz. the amulets, maṇis and water. Atharva-Veda , 1. 4.4,1. 5,1. 6,1. 33, vi. 24, vi. 92, etc. are all in praise of water as medicine, and water is regarded there as the source of all rasa or taste. Thus from the earliest times two different kinds of medicines were used. Of these the amulets were more or less of a miraculous effect. It was not possible to judge which kind of amulet or maṇi would behave in which way; their mode of operation was unthinkable (acintya). It is easy to see that this mode of operation of medicines was what was considered a prabhāva by Caraka and Suśruta.

With them prabhāva means the mysterious operation of a medicine acting in an unaccountable way, so that, though two medicines might be exactly similar in rasa , vlrya and vipāka , they might behave differently with regard to their medicinal effects^[17]. Such an effect was thus naturally considered as unthinkable. But the analogy of the old maṇis was fresh in the minds of these medical thinkers when conceiving this prabhāva , and it was in reality an extension of that idea to other unaccountable effects of medicines^[18].

As none of the chemical effects (in the modem sense) of medicines on human organs were known, the most obvious way in which the medical effects of herbs, roots, etc. could be classified was on the basis of taste, and by Caraka and Suśruta we are told the effects of the different rasas on the different morbidities of the body, vāyu, pitta and kapha.

As the main source of all diseases was unequal increase or decrease of vāyu , pitta and kapha, a classification which described the rasas in such a way that one could know which rasa increased or decreased which of the morbidities was particularly useful. But it is obvious that such a classification, though simple, could not be universally true; for, though the taste is some indication of the medicinal property of any substance, it is not an infallible one. But no other mode of classification was known; it was supposed that the taste (rasa) of some substances changed altogether after digestion and that in such cases the taste which changed after digestion (pāka) would be operative.

Cakrapāṇi says that in those cases where the taste on the tongue (rasa) agrees with the taste as produced after the digestive process, the effect in that direction becomes very strong, but in the case where the latter differs from the former the operation of rasa becomes naturally weak, because the force of the taste produced by the final operation of the digestive process is naturally strong^[19].

Caraka thought that there were only three rasas as the result of digestion, viz. katu, madhura and amla ; Suśruta rejected the last, as has already been described. But even this was not sufficient; for there were many other effects of medicine which could not be explained on the above suppositions. In explaining this, the theory of vīrya was introduced. In addition to taste substances were considered to possess other properties of heat and cold, as judged by inference, tactual properties of slipperiness, movement, moisture and dryness, etc., sharpness, etc. as manifested by odour, and these were supposed to produce effects in supersession of rasa and vipāka. It was only in the cases where no sensible data of any kind could be found to indicate the medical properties of the thing that the idea of prabhāva was introduced.

The chapters in Āyurveda on dravya and guṇa deal with the enumeration of prabhāva and also of rasa, vipāka and vīrya wherever there is a divergence among them, as determined by empirical observation. This is very necessary not only for the selection of medicines and diet in the cure of diseases, but also for prevention of diseases. It is well to remember that many diseases were supposed to arise through eating together things which are opposed to each other in rasa, vipāka or vīrya.

Footnotes and references:

[1]:

Thus mudga (a sort of kidney-bean), which is a bḥūta-vikāra, has the rasas of astringent and sweet and is yet light by nature, though one would expect it to be heavy on account of its rasas of astringent and sweet. Vikṛti is best exemplified in the case of fried paddy, which is lighter than rice. It is well known that by composition wholly new properties may be generated in the product. Medicinal herbs vary in their properties in accordance with the time of plucking.

[2]:

The medicinal effect of substances may be distinguished from the medicinal effect of qualities, as when by certain stones (maṇi) poison may be removed or by the use of certain amulets certain diseases may be cured. Again, there may be cases where simply by the application of heat a certain disease may be cured, irrespective of the substance which possesses heat as its property. It seems that only the sense-properties and mechanical properties are here counted as guṇas ; other kinds of properties were considered as being due to the thing (dravya) itself.

For, in addition to the sense-properties, the twenty qualities,

1. guru,
2. laghu,
3. śīta,
4. uṣṇa,
5. snigdha,
6. rūkṣa,
7. manda,
8. tīkṣṇa,
9. sthira,
10. sāra,
11. mṛdu,
12. kaṭhina,
13. viśada,
14. picchila,
15. ślakṣṇa,
16. khara,
17. sūkṣma,
18. sthūla,
19. sāndra
20. and drava,

are counted as guṇas (Caraka-saṃhitā , I. i. 48; 1. 25. 35; 1. 26. 11).

[3]:

Iha ca kāraṇatvaṃ bhūtānāṃ rasasya madhuratvādi-viśeṣa eva nimitta-kāraṇatvam ucyate.
      Cakrapāṇi on Caraka, 1. 26. 38.

[4]:

Caraka-saṃhitā, 1. 1. 47. Even trees were regarded as being possessed of senses and therefore animated or cetana. Cakrapāṇi says that, since the sunflower continues to turn its face towards the sun, it may be regarded as being possessed of the sense of sight; again, since the lavah (Averrhoa acida) plant fructifies through hearing the sound of thunder, the plants have auditory organs, etc.

[5]:

Ibid. 1. 1. 47, 48 and 50, with Cakrapāṇi’s commentary.

[6]:

Caraka-saṃḥitā, i. 26. 39, Cakrapāṇi’s commentary.

[7]:

Suśruta, Sūtra-sthāna, 4.0.2. Dravya is defined by Suśruta as kriyā-guṇavat samavāyi-kāraṇam.

[8]:

iḥauṣaḍḥa-karmāṇi ūrḍhvāḍho-bhāgobhayabhāga-saṃśoḍhana-saṃśamana-saṃgrāhakāgni-dīpaina-prapiḍana-lekhana-vṛṃhaṇa-rasāyana-vājīkaraṇa-śvaya-thūkara-vilayana-dahana-dāraṇa-mādana-prāṇaghna-viṣa-praśamanāni vīrya-prāḍhanyāḍ bhavanti.
      Suśruta, 1. 40. 5.

[9]:

etāni khalu vīryāṇi sva-bala-guṇotkarṣāt rasam abhibhuyātma-karma kurvanti. Suśruta, ibiḍ. The vīrya is said to remain both in the dravya and in the rasa. Thus in Suśruta, 1.40.5-8, it is said that, if in those rasas which remove vāta there is dryness (raukṣya), lightness (lāghava) and cold (śaitya), then they will not remove vāyu ; so, if in those which remove pitta there is sharpness (taikṣṇya), heat (auṣṇya) and lightness (laghutā), then they will not remove pitta, and so on.

[10]:

caturṇām api sāmagryam icchanty atra vipaścitaḥ. Suśruta, I. 40. 13.

[11]:

dravya-śakti-rūpakā rasa-vīrya-vipākā yathā-yogaṃ nimitta-kāraṇatātn samavāyi-kāraṇatāṃ vā bhajanto na kartṛtayā vyapadiśyante dravya-parā-dhīnatvāt.
      Bhānumatī , 1. 40. 13.

[12]:

dravyam ātmanā śaktyā prabhāvākḥyayā doṣaṃ hanti .. .atra dravya-śakti-kāryodāharaṇamyathākarṣaka-maṇir loha-śalyam ākarṣati.
      Bhānumatī, 1.40.13.

[13]:

tasya pākasya tad-rasasya vipākasya ca pṛthañ-nirdeśān na vīrya-vyavahāraḥ śāstre.. .Carake tu sāmānya-vīrya-śabdena te ’pi grhītāḥ.
      Ibid. I. 40. 5.

[14]:

yadā dvividhaṃ vīryam tadā snigdha-rūkṣādīnāṃ... rasādi-dharmata-yaiva kārya-grahaṇaṃ vakṣyati hi madhuro rasaḥ snigdha ity ādi aṣṭavidha-vlrya-pakṣe tu... balavat-kārya-kartṛtva-vivakṣayā vlryatvam iti sthitiḥ.
      Ibid. 1.40.

[15]:

Aṣṭāṅga-hṛdaya, 1. 9. 15.

[16]:

Ibid. 1. 28.

[17]:

rasa-vlrya-vipākārtaṃ sāmānyaṃ yatra lakṣyate viśeṣaḥ karmaṇāṃ caiva prabhāvas tasya ca smṛtaḥ.
      Caraka-saṃhitā, 1. 26. 69.

Cakrapāṇi, in commenting on this, says,

“rasādi-kāryatvena yati nāvadhārayituṃ śakyate kāryaṃ tat pra-bhāva-kṛtam iti sūcayati; ata evoktaṃ' prabhāvo 'cintya ucyate’ rasa-vīrya-vipāka-tayācintya ity arthah.”

[18]:

maṇlnāṃ dhāraṇīyānāṃ karma yad vividhātmakaṃ, tat-prabhāva-kṛtaṃ teṣām prabhavo ’cintya ucyate.

(The various actions of amulets are to be considered as being due to a prabhāva which is unthinkable—
      ibid. 1. 26. 72.)

[19]:

Cakrapāṇi on Caraka, i. 26. 65. Cakrapāṇi points out that the hot (kaṭu) taste is at first useful in cleaning the phlegm of the throat, but, since it becomes sweet after digestion, it acts as a nutrient (vṛṣya). But, except in the case of such local actions, it is difficult to understand why the rasa which was altered by digestion should have any such effect as Cakrapāṇi suggests (viparyaye tu ḍurbalam iti jñeyam).