The Physiology of the Nervous System According to the Hindus.

By P. T. Srinivasa Aiyengar Esq.

1. WHAT IS PRANA?

    European physiology, notwithstanding its wonderfully rapid development in the 19^th century, has not been able to make up its mind about the nature of a nervous impulse. How the vibrations of ether and of air that produce the sensations of light and heat and sound, how the solutions of molecules producing taste in the mouth, the gases that cause smell in the nostrils, affect the nerves, and how that effect is transmitted along them, are questions about which nothing has been discovered.

    Says Mr. McDougall (in his Physiological Psychology, published in 1905): "As to the essential nature of this '(nervous) impulse' we are still ignorant… It is still, and probably for a long time to come will be, impossible to define the nature of the 'nervous impulse' in physical or chemical terns; … it is possible that it involves a form or forms of energy with which we have no nearer acquaintance…Every part of each neuron is irritable, i.e., capable of responding to a stimulus with a katabolic change which initiates a 'nervous impulse.' This katabolic change results in the conversion of chemical potential energy into free nervous energy… But the process of liberation of energy in the neuron differs from processes of a similar kind that occur outside living tissues in one very important respect, namely, the quantity of energy liberated in the neuron varies with the intensity of the stimulus."

    Hindu writers think that this "nervous impulse" is a wave of a subtle fluid, called Prana, in the 'subtle body.' Prana flows in minute tubes, called Nadis. This flow is conceived as the conduction of "fluid-wave of pressure in a pipe," exactly as some European physiologists understand a "nervous impulse" to be. A few of these Nadis are visible in the "gross body," e.g., the central canal of the spinal cord and the medulla oblongata, and the ventricles of the brain, but the rest, those that correspond to the nerve are invisible. This Prana has been generally mistranslated as the "life-principle" of the Vitalists of European biology; but the mistake is due to the fact that, so long as the Prana is flowing in the Nadis, i.e., "nervous impulse" flow along the nerves, an animal lives, and when the Prana stops, the animal dies.

    European biology makes the flow of "nervous impulses depend upon the flow of blood in the blood-vessels, and assumes that the circulation of blood is a condition precedent to nervous action. This is an unprovable assumption, since without nervous action the heart cannot act; the assigning of priority to the flow of blood is a pure assumption, and the Hindu conception of the priority of nervous action is equally valid.

    Prana is not a life-principle, but a "nervous impulse," conceived as a flow of subtle matter in nerve tubes, for the Pranas are always located in the Nadis. Prana is also frequently confounded with breath, especially by Hindu scholars. This is again a case of erroneous translation; for breath is air going into and out of the lungs, and Prana is never spoken of as flowing into the lungs but always as flowing in the nerve tubes. The mistake is due to the fact that the breath, in normal conditions, flows at any time through one nostril; and this is attributed by the Hindu to some cause traceable to some fact in the nervous system.

    The flow of breath through one nostril at a time is taken as indicating a corresponding flow of Prana in the nerves on which depend the life-processes of the animal; hence the breath in the nostrils (and not in the lungs) is sometimes loosely spoken of as Prana. Moreover, the flow in the Nadis being the conduction of a pressure wave as in a gaseous medium, Prana, the substratum of this wave, is conceived as a gas and spoken of as Vayu.    

There are two kinds of Vayu: (1) Panchikrita-vayu, "molecular air," or compound gas, like the air of the atmosphere; and (2) Vayu-tanmatra, "atomic air,: elementary gas, the substrate of the sensation of touch. Prana is similar in nature to Vayu of the latter kind.

As the Sankhya Pravachana Bhashya says: "Though the Prana is a transmutation of the internal instruments (i.e., of Buddhi Ahamkara and Manas), it is justifiable to speak of it as Vayu, because its motion is similar to that of Vayu, and it is under the control of the Deva Vayu."

The Brahma-Sutras (ii. 4, 8) also say: "It is neither air nor a function (of air)"; for in the Mundaka Upanishad (ii. 3, 1) it is said "from it is produced the Prana, the mind, and all organs of sense, ether, air, light, water, and earth, the supporter of all."

In explaining this Sutra, Shankara and Ramanuja both point out that Prana is frequently called air, because the substance of Prana is a special, or Adhyatma (noumenal), condition of air. Its essence is not water or fire, but air, though it is not identical with the air (in our lungs or that blowing round us).    

I will close this discussion with two quotations which allow without a possibility of doubt, that Prana is nothing but what we call nerve-action.

Brihad Up. (i. 3, 19) says: "From whatever limb Prana goes away, that limb withers." Again, Shankara says in Sutra Bhashya (ii. 4, 9). "Prana is the oldest, because it begins its function from the moment when the child is conceived."

This can refer only to the nervous action that presided over the vital process of the fetus, and not breath.    

The above quotation from Sankhya Shastra indicates that Prana is "subtle" matter of the grade of Buddhi and Manas. Physical matter, that which can be observed by our senses, is believed by Hindu philosophers to be Panchi-krita, compounded of five ultimate elements called Tanmatras, the objective bases of sensations. Buddhi and Manas are a grade of matter subtler than these and Prana is of this grade.

Vachaspati Mishra says: "The five Pranas, or life, are the function of the three instruments (Buddhi, Ahamkara, Manas), from being present where they are, and absent where they are not."

The Vedanta would make Prana superior to these, Says Shat. Brah. (vi. 1, 1, 1):

"Non-being (Asat) indeed was this in the beginning, they say. What was that Asat (Non-being)? These Rishis indeed were the Non-being in the beginning. They say: Who are those Rishis? The Prana indeed or the Rishis."

Brihad. Up. (ii. 1, 20) says: "As the spider comes out with its thread, as small sparks come forth from fire, so from that Atma, all Pranas, all worlds, all senses (Devas), all beings come forth. Its (the Atma's) secret name is the 'Truth of truths.' The Pranas are truth. Of them, It (the Atma) is the Truth."

Thus, according to the Vedanta conception, Prana is the highest grade of natter, and the first objective basis of Atma.

II. THE DIFFERENT KINDS OF PRANA.

Prana is a generalized conception. In the body, it is specialized into various kinds of Pranas. They are of three classes: (1) the Mukhya Prana; (2) the five Pranas of physical life; (3) the eleven Pranas of psychical life.

(1)    The Mukhya Prana is the chief Prana. It is the first objective manifestation of Atma (the spirit). This latter can be reached only by introspection (Pratyag-drishti). It reveals itself to objective contemplation as Mukhya Prana, the power which underlies the life of each Bhuta, or concrete object of the mineral, animal or vegetable kingdoms. It builds the crystal, and enables vegetables and animals to carry on their life-functions.

It is called in the Vedas Jyeshtha, Shreshtha, Vasishtha, Pratishtha – the oldest, the best, the richest, the best placed, and so on. The great Rishis of the Rig-veda are identified with it by ingenious etymologies invented for their names (vide Aitareya Aranyaka, ii. 1).

It is identified with Brahman, with Indra, and with Prajna in the Kaushitkai Upanishad. It is the highest order of material Non-being, impermanent being, the oldest of the phenomenal manifestation of the universe. It is the presiding life, the binding unity that makes any collocation of atoms into an object.

When the Self-begotten, Svayambhu, thought: "May I become many," – Mukhya Prana was the objectivities of that Will to become many. It is the life of the universe.

In this cosmic aspect, this Mukhya Prana is called Hiranyagarbha, and described as being "equal to a grub, equal to a gnat, equal to an elephant, equal to these three worlds, equal to this universe." Brihad. Up., I. iii. 22.)

In the individual man, Mukhya Prana is the objective representative of his Atma.

As Shankara says, in the Brahma-Sutra Bhashya (II. iv. 16): "And only with the embodied soul the Pranas are permanently connected, as it is seen that when the soul passes out, etc., the Pranas follow it."

This we see from passages such as the following: "When he thus departs, the (Mukhya) Prana passes out after him, and when the Prana thus passes out, all the other Pranas pass after it." (Brihad. Up., IV.iv.2)

Thus this Mukhya Prana corresponds to the life-principle of European Vitalists, but is different from it, in that Buddhi, Ahamkara Manas (which European philosophy treats as faculties of the subject, of the ego), are, with us, aspects of this Prana. It is the highest order of discrete being, the material aspect of Sat, the objective concomitant of Prajna.

Says the Kaushitaki Upanishad (iii): "Indra said: 'I am Prana, meditate on me as the conscious self (Prajnatma).' What is Prana, that is Prajna (consciousness); what is Prajna, that is Prana; for together they (Prajna and Prana) live in this body and together they go out of it…And that Prana indeed is the self of Prajna, blessed, imperishable, immortal."

This Prana resides in the cave of the heart. Prana, being Sukshma, subtle, minute, resides in the subtle body. The part of the subtle body corresponding to the windpipe, conceived as extended to the epigastria region, is the cave where it plays. From the uvula to the center of the chest, the length of a man's thumb, it plays in the Akasha atomic matter of the most tenuous kind and on its play depend the discharge of the vital functions and the display of consciousness in the body,

European physiology teaches us that the vital functions depend upon the beating of the heart and the periodical discharge of the blood from it. But no force – nervous or otherwise – has been discovered which causes the heart to contract rhythmically; so much so, that it is said "that the muscle-substance of which the heart is made, is itself endowed with the power of contracting and relaxing at regular intervals" – a most unsatisfactory conclusion, since all other muscular contraction depends on the action of some nerves.

The Hindu would explain that the rhythmic beat of the heart is the work of this Mukhya Prana. The quotations already given from the Shruti bear this out. It is a much better explanation of the beating of the heart than that of modern physiology, which has practically given up the problem as hopeless.

The circulation of blood is the chief function of Mukhya Prana only from the point of view of physiology; Buddhi, Ahamkara and Manas also depend upon it. As Madhvacharya explains in his Sutra Bhashya, the elements function, and the Vedas, and all this world, came forth from this Prana. This Prana in the man is the analogue of the sun in the cosmos. Pippalada (Prashna Up. i) quotes an ancient Rik which says: "Who assumes all forms, golden, the knower of all things, the highest, alone in splendor, the warmer, the thousand-rayed, who abides in a hundred place, the Prana of creatures, the sun rises." In Prashna Up., iv., these sun is called the external Prana.

It has already been pointed out that the Mukhya Prana is golden, immortal, and called Hiranyagarbha in the cosmos. As the golden Prana is the objective manifestation of the Atma in the body, so the golden Person imagined to be in the sun, is the objective manifestation of the Lord of the solar system. As the Prana supports the life of the body, so the solar energy supports the life of the solar system, of which the sun is the heart.

Says the Maitrayana Upanishad, vi: "He (the Self) bears the Self in two ways, as he who is Prana, and as he who is Aditya…The Sun is the other Self; the inner Self is Prana…For thus it is said: "He who is within the sun is the golden Person, who looks upon this earth from his golden place; he is the same who, after entering the inner lotus of the heart, devours food."

Rig-veda (i. 164, 13) makes the same identification. Says a Rishi there: "I saw Prana as a guardian, never tiring, coming and going on his ways (the Nadia). That Prana (in the body being the same as the sun among the Devas) illuminating the principal and intermediate quarters of the sky, is returning constantly in the midst of the worlds."

Either in the body of man or in the body of the solar system, it is the support, the life-giving power of the Lord, his higher nature, by which, according to the Bhagavad Gita, "all this universe is upheld."

As Madhvacharya says: "Prana in the body or the cosmos is verily the middle for it is between all beings on the one side and the Supreme Lord on the other, and is hence the highest form of discrete Being in the manifested worlds."

(2)    The five Pranas. This Mukhya Prana is differentiated into five kinds, for the purpose of discharging the various functions of physical life. I have already pointed out that European physiology has not yet understood the nature of a "nervous impulse." Hence, it is not likely to admit of a five-fold sub-division of it; but this is what the Hindus teach. The five sub-divisions of nervous energy connected with organic life are Prana, Apana, Vyana, Samana, and Udana. They are five modifications of Mukhya Prana, that circulate (syand is the Sanskrit verb used to indicate this idea) in the nerve tubes and keep up the life-functions.

Prana, the first of these, is to be distinguished from Prana used for a nerve impulse in general, or again for Mukhya Prana. This Prana is said to reside in the region between the heart and navel of the subtle body and to rise upwards and cause respiration.

It is curious that physiology also makes normal respiration primarily depend on afferent impulse going along the vagus nerve to the respiratory center in the medulla oblongata, taking exactly the course that Prana is said to take in Indian books to cause respiration (vide Starling's Human Physiology, pp. 388-394).

This Prana is said to be red in color and bright like a jewel.

Apana is the nervous energy presiding over the functions of the kidneys the large intestines and the testes, and helps the expulsion of their products. It starts from the region of the semilunar ganglion, and corresponds to the nervous impulses starting from the lumbo-sacral (spinal) nerves, and circulates through the sympathetic ganglia and nerves connected therewith. This Apana is said to be of Indragopa (cochineal) color, Prana and Apana rest, as it were, on each other, normally pulling away from each other and thus keeping each other in possession.

Vyana circulates through the seventy-two crores and odd minute Nadis. It maintains the general functional equilibrium of the body. Vyana is also said to abide in the junction of Prana and Apana. It is brought into play when doing "works of strength"; one holds in the breath and compresses the muscles at the lower half of the trunk. According to Gandapada, by Vyana "internal division and diffusion through the body are effected." It is flame-colored. It perhaps corresponds to the nervous energy of the vaso-motor system.

Samana presides over the digestion and distribution of the "subtle (digested) food to the tissues. It will hence correspond to the nervous energy of the sympathetic system connected with digestion and the supply of food and oxygen to the tissues. It is of the color of cow's milk.

Udana presides over the head, neck, and temples, while a person is alive. At death, it leads the Prana via the third ventricle, to the anterior fontanelle and out of the body. It is of a pale yellow color, and presides over the organic life of the head.

Possible the macrocosmic correspondences of these five Pranas will help us more easily to comprehend their functions. This Prana in the cosmos is the sun; Apana is the earth; the supporter of all; Vyana is all-pervading air; Samana the Akasha, and Udana light.

(3)    The eleven Pranas. These are the nervous energies of psychical life, that of sensation, voluntary action and thought. The Pranas of the Jnanendriyas are those that flow in the olfactory, gustatory, optic, tactile and auditory nerves. At the sensorium, where these nerves take their rise, the substrata of these five sensations reside. Thus where the olfactory nerves take their rise, there is Gandha-tanmatra, lit. "smell pure and simple," an elementary substance which by various combinations called Panchikarana, or quintuplication, becomes earth, and so on for the other four sensations.

Thus when the Hindu speaks of Akasha being Shandatanmatra, people mistranslate the statement into sound consisting of vibrations of Akasha, and ridicule the Hindu Naiyayikas on that account. It properly means that Shabda-tanmatra, the pure sensation of sound, or rather the elementary matter where it inheres, viz., Akasha, resides in the sensorium, and the same Akasha, being mixed with air, etc., forms the compound Akasha all round us.

European physiology cannot explain how sound, which is a vibration of air, can become a sensation inside us. Indian Nyaya says that the sound we hear and the sound outside us are in the same elementary substance, called Akasha. Surely the Hindu explanation is sound as an explanation, only it cannot be proved by the canons by which physical facts are proved, because the elementary substance involved in the explanation is super-physical.

The five sensations, then, depending on five Tanmatras, super physical elements, the Prana corresponding to them are five-fold. The five Karmendriyas are the five sets of voluntary muscles, those concerned in speaking, grasping with the hands walking, evacuation, and emission.

The eleventh Prana is that of Manas, the nervous energies concerned with thought. Manas is here used in a loose way to indicate what the subtle analysis of the Sankhyas discriminates as Buddhi, Ahamkara and Manas proper, which roughly correspond to will, self-consciousness and formative imagination or perceptive faculty (Adhyavasaya, Abhimana, Sankalpaka); and these mental functions are associated with the play of three modifications of a certain kind of Prana of the highest grade of matter.

In Indian philosophy the internal mental functions and objective play of Prana are inseparably associated with each other. One is not the cause of the other; there is no question of precedence between them.

This Prana plays in the cavities of the brain (the ventricles), and also in the Sushmna, the central canal of the spinal cord. As described in the Taittiriya Up. (I, vi): "Between the palates it (the uvula) hangs like a nipple – that is the birth place of Indra. Where the root of the hair divides, there he opens the two sides of the head (he enters Agni, Vayu, Aditya, and Brahman)…He there obtains lordship, he reaches the lord of the Manas. He becomes lord of speech, lord of sight, lord of hearing, lord of Vijnaha (knowledge). Nay, more than this; there is the Brahman, whose body is Akasha, whose nature is Truth, who rejoices in the Pranas, is delighted in the mind, is perfect in peace, immortal. Worship thus."

A more detailed description of this supreme Prana cannot be attempted as it is the object of this article to give only a general view of the subject.

III. THE NADIS.

The Nadis are the tubes of nervous matter, in which the Prana flow. They are of two classes, those connected with involuntary action, with man's physical life, which does not normally show itself in his consciousness, and those connected with voluntary action, with his psychical life, bound up with his consciousness. It has been already pointed out that psychical life (i.e., the Prana corresponding to Manas) resides in the cavities of the brain. Its center is the third ventricle, whence it acts all through the brain, innervating the eyes, ears and the organ of smell, and down the front of the pharynx and tongue to cause voice and help to sense taste, and down the back, along the spinal tube, sub serving the sense of touch, and the four Karmendriyas except Vak (voice). These two tubes from the third ventricle are each called Sushumna.

On the sides of the Sushumna in the spinal tube are the Ida and the Pingala, through which currents of Vayu-tattva ("atomic air") and Agni-tattva ("atomic fire") flow. When the Ida is active the Pingala is passive and vice versa. According to Hindu ideas, when the Ida is active the breath flows through the left nostril; and when the Pingala is active the breath flows through the right nostril.

It is curious that this fact – that while both lungs act always, the breath plays normally only through one nostril at any given moment, and that there is a periodical alternation of the flow through the right and left nostrils – seems quite to have escaped the notice of European science.

Besides these two, ten other Nadis parallel to them are mentioned. These twelve extend from the Region of the lumbo-sacral enlargement of the spinal cord to the floor of the fourth ventricle – the Dvadashantam (the end of the twelve).

The Nadis conveying the Prana of organic life correspond to the sympathetic system. The peculiarity of this system is that the nerves at various places enter into ganglia, where they seem to be reinforced. Five of these ganglia are given great prominence in certain forms of Yoga that deal with the animal non-mental life of man. They are Muladhara (sacral), Svadhishthana (hypogastria), Manipura (solar), Anahata (stellate), and Vishuddhi (superior cervical).

Besides these, the six plexuses in the course of the spinal cord seem to be connected with the higher forms of Yoga, but that is a subject about which very little is taught in books.

- The Theosophical Review.