THE NATURAL BASIS
THE LYMPHATIC SYSTEM
The correspondences of the lymphatic system are explained by reference to people in the next life whose work is like that of the lymphatics in the body
196. The lymphatic system is not one which receives much attention in elementary biology, as it is difficult to see without special techniques. Nevertheless it is an essential part of the body's make up. In the Writings its correspondences are explained by characteristics of people in the next life whose functions there are like the functions of the lymphatics in the body. Much of what is said in the Writings about the correspondences of certain organs is related in this way, and different classes of people are said to belong to different provinces named according to the corresponding organs. The activities and interrelations of these different classes follow so closely the activities and interrelations of the bodily organs that the people (or spirits) are often described as if they did actually belong to the organs themselves. Indeed every one in heaven and many in the spiritual world are part of one great human organization or, rather, organism.
197. To those who are not familiar with these things
it must seem very strange that, on passing into the next life, human souls
find themselves becoming members of one human organism. However, they continue
to live amongst appearances like those of this world (HH 171), and it is
not the appearances amongst which they live, but the genuine inner reality
of their life and functions that corresponds to the human form. Here, by
"human form" we wish to convey an idea not precisely limited, but one which
begins with anatomy (which is a matter of shapes, sizes, and relations)
and progresses to physiology (which includes functions and dictates the
anatomy), and thence climbs to psychology and spiritual doctrine which
teach about the human form of heaven. For the human form of man exists
only because the essentials of the human form of heaven flow into it. Similarly,
heaven derives its human form from the Lord. Hence a study of the human
form is an eminently rational way to comprehend the organization of heaven
(and of every regenerate man who is a heaven in the least form). This can
nowhere be seen more clearly
198. When one has become accustomed to the assignment of various spirits (i.e.,people) to societies which correspond to the functions of particular organs, one is not surprised to read that there are some spirits that correspond to the lymphatic system, since it forms such an important part of the body's economy and defences. (But one cannot fail to be continually surprised and delighted at the opening of new ideas when the revelations of the Writings are applied to modern knowledge.) In the case of the lymphatic system, the result is all the more gratifying in view of the sparseness of references to it in the Writings. A brief study of the lymphatic system as it is now known is, of course, a necessary preliminary to the appreciation of its correspondences.
199. Throughout most parts of the body there are many microscopic tubes which begin blindly in spaces between cells and form a network analogous to that of the blood capillaries. These are the lymph capillaries. In their course through the tissues they join together and become larger and easier to see, but still they are thin-walled and their contents are colourless so that only a few of the largest can be seen without the use of special techniques (e.g., the injection of dyes). The large vessels also join one another in their turn and most of the main trunks thus formed lead to the thoracic duct which pours its contents into the jugular vein at the base of the neck. See Figure 9.
200. It is assumed that the receptacle and ducts
of the chyle mentioned in AC 5180 are approximately equivalent to the lymphatic
system. This is because they are part of it, the only difference being
that the ducts happen to run in the mesentery near the intestines and even
into the intestinal walls themselves so that they are able to absorb fat-globules
from the digested food. The fat acts as it does in milk, making the fluid
in the ducts white and milky and causing these ducts to be more easily
visible than others. (Hence they were classed separately as lacteals.)
The connection between the lacteals and the other lymphatics is seen in
AC 5181, which notes the movement of spirits who belong to the province
of the lymphatics. We find that they "are afterwards conveyed into places
which, they said, have reference to the mesentery, and where I was told
that there are as it were labyrinths, and that they are afterwards taken
away to various places in the Grand Man to serve for use, as is done
201. The origin of tissue fluid by seepage through the walls of blood capillaries was described above (No. 76). Most of this fluid drains back into the blood stream at sites where the pressure inside the capillaries is lower. (These are the capillary sections distal to the arteries and nearer to the veins.) There remains, however, a residue of fluid to which are added any substances produced by the activities and breakdown of the tissues. The resulting mixture is the lymph which is collected by the system of ducts described above.
202. There is no pump to cause a flow of lymph, and its movement is quite slow (in contrast to that of the blood). Movement does occur because all muscular activity produces fluctuations of pressure in the tissues. Moreover the squeezing effect causes flow only in the required direction because the ducts contain many valves which prevent the reverse flow. In places, the effect is augmented by the pulsation of nearby arteries, and everywhere the pressure of fluid in the tissues (derived from the pressure of the blood) is higher than the blood pressure at the point where the lymph ducts open into the blood stream. An example of this is in the veins of the neck where the blood is, as it were, merely falling towards the heart. Thus there are several factors which ensure that the flow of lymph, though slow and gentle, is certain. The gentle flow is linked with the state of souls who belong to the province of the lymphatics. In the words of the Writings their "gyres…are slight and rapid like gently flowing water so that scarcely any gyrating can be perceived" (AC 5181).
203. Lymph vessels differ from blood vessels in being able to admit particles through their walls. Such particles are only microscopic but still millions of times larger than the molecules which normally pass through the walls of blood capillaries. There is a wide range of particles which can be found in lymph, but the most important are: (1) debris from the decomposition of worn-out cells in the tissues, (2) bacteria and other micro-organisms which invade the body from time to time, and (3) various wandering cells which have important functions in the blood and other tissues. All these particles drift into the lymph ducts with the stream of tissue fluid. From this it can be seen that the lymphatic system works like a slow motion vacuum cleaner "sucking up" all kinds of materials, good and bad, from almost every site in the body.
204. There is no use in collecting waste unless its disposal can also be arranged. This is done efficiently in the lymphatic system. At frequent intervals in the network of ducts there are nodes. These are small bodies containing spongy material through which the lymph must flow. The spongy substance is made of microscopic threads and these are partially covered with scavenger cells which, acting like amoebae, swallow any particles that come to them. Hence they are known as phagocytes (also as macrophages). They remove from the lymph all kinds of microscopic particles, even scraps of carbon or metal, if present, but normally such materials as residues from effete body cells and bacteria. There are also some phagocytes that leave their filamentous supports and are swept along with the lymph into the blood where they continue their function. Figure 10 illustrates in detail the structure and organization of the lymph node.
205. Some of the phagocytes have a special ability to penetrate the walls of capillary blood vessels, by which means they reach tissues that would otherwise remain uncleansed. They are particularly important in the lungs, from which they remove dust particles drawn in during respiration. (Dust particles act as vehicles for many bacteria, which, unless they were killed, would choke the lungs with harmful growth.) Phagocytes digest many of the particles they take in, but this is not always possible, and in such a case the cells provide a degree of protection by isolating the particles. Carbon, for example, is indigestible, so that even if absorbed by phagocytes it remains, and the lungs of people who live in smoky districts change from the pink colour of childhood to grey in old age. When the protection by isolation is inadequate, serious consequences ensue, as in cancer of the lungs caused by smoking, silicosis, and so on. If they are not poisoned by the particles they ingest, the phagocytes find their way back into the blood stream through the lymphatic system.
206. Although we regard the lymphatic system as the source of immunity, the protection immunity provides occurs in all parts of the body. This is due to the activity of yet other kinds of cells which float in great numbers in lymph and blood. These cells or lymphocytes are produced largely in the spleen, but also in lymph nodes. They spend part of their time entangled among the microscopic threads of the nodes but eventually they break free and travel with the lymph into the blood stream. Chemically speaking, their activities are as varied as the diseases and poisons to which the man is immune, and the subject of immunity has many complexities. Although a summary cannot do justice to such a subject, a brief account will suffice to indicate possible new ways of looking at the correspondences. Immunity is an ability to cover foreign molecules in the body with a coating like the veils mentioned in AC 963 and 964.
207. When foreign substances enter the body (i.e., when they gain access to the tissues, not when they are merely in the stomach or intestines), they are dealt with in a variety of ways. Those that have large molecules (or that become attached to large molecules) often stimulate the production of immunity. They are called antigens which name merely indicates that they normally cause the immune reaction. Many of them are produced by bacteria or other microscopic organisms which may grow in or on the body. The immune reaction itself consists in the production by the body of new substances with molecular shapes which enable them to "lock on" to the antigen and form a blanket, thus sealing off each antigen molecule so that it cannot exert any harmful action. The substances with these new molecular shapes are antibodies. They can be isolated from the blood of immune individuals and their "blanketing" activities can be demonstrated in the laboratory. Because the action between antibody and antigen depends on the molecule of one fitting onto the molecule of the other, each antibody is very specific; it will combine only with its "own" antigen. Hence immunity to each toxin or disease must be developed separately.
208. Immunity to disease caused by bacteria is often acquired by becoming immune to substances which form the coat of the bacterial cell. Then the particular specific antibody covers the bacteria so that they have a different surface. This can have a number of conse-quences: The disease-producing or toxic properties may be neutralized, the growth of the bacteria may be interfered with, they may be unable to disperse or spread, and they may become easier for the phagocytes to swallow. This last is a specially important consequence, for there are some bacteria which resist the phagocytes, but after immunity has developed, such bacteria may be covered with antibodies and they are then readily devoured.
209. Diseases correspond to evils and falsities, that is, to people in the spiritual world who are evil and false and especially to those in hell (AC 5172). Quite a large group of diseases appear to be caused by bacteria and viruses, so that in considering the spiritual causes behind these natural phenomena we readily identify evil spirits as correspondences of disease-producing bacteria, and we do not have to search far to find a correspondence of the immune reaction. The blanketing part of the immune process, seen from the molecular level, is irresistibly similar to the veiling of evil spirits described in AC 963 and 964 where we read that the veil "is like a closely clinging cloud that increases in density in proportion to the phantasy." This is just like the antibody molecules clustering round a bacterium, attaching themselves in greatest numbers where the antigen molecules are most numerous.
210. The kind of immunity we have been discussing is acquired after exposure to an antigen, and it is well known that the range of possible immune reactions is very wide. Why is it that complete immunity to one disease, say, whooping cough, in no way diminishes an individual's ability to become immune to some other toxin or microbe, such as tetanus, for example? The answer to this very puzzling question lies with the lymphocytes.
211. Lymphocytes do not manufacture antibodies until they meet a foreign protein, carbohydrate, or other antigen. They then elaborate a certain antibody and become so committed to this particular process that they are unable to make any other antibody. Their activities will, however, in due course remove all that particular antigen so that new lymphocytes (which are continually being produced in the spleen and nodes) will remain uncommitted until another antigen appears. Thus it is that in health the body always has a good stock of uncommitted lymphocytes to meet any new invasion, but many of those circulating in the blood and lymph will be already committed.
212. The inability of lymphocytes to change reminds us of the persistence of certain spirits of this province who are also said to be impudent and of a wandering kind. In AC 5180:2 we read that they never give way, further that they "keep the others as it were in bonds and under their control," which is like the effect of antibodies on foreign cells. The phrase, "being privy to their evils," reminds us of the ability of lymphocytes and phagocytes to detect any kind of irregularity which would label a cell or a substance as foreign. The impudence of some of the spirits is matched by the readiness of the phagocytes to swallow any foreign particles that come their way, an impudence which is their undoing when the particles happen to be poisonous.
213. The lymphatic system must, of course, include the phagocytes and
lymphocytes, for they are living cells in the system. Their motion in the
lymph and subsequently in the blood stream means that they wander into
all parts of the body. Of the two kinds of spirits that belong to the receptacle
and ducts of the chyle, only the impudent ones are of the wandering type.
We regard the receptacle and ducts of the chyle as equivalent to the lymphatic
system (No. 200), but it is difficult to say how far we may go in relating
bodily phenomena with spiritual activities. Can we think that spirits of
a wandering kind correspond to cells that are mobile and only to such?
The next number (AC 5181) suggests that here at least we may do so, for
we read that "They who belong to the lymphatics are afterwards conveyed
into places which they said have reference to the mesentery and where I
was told there are as it were labyrinths, and that they are afterwards
taken away to various places in the Grand Man to serve for use as is done
with the chyle in the body" (emphasis added). If the movement of the spirits
corresponds to the movement of the chyle, the wandering kinds of spirits
would correspond to the living cells in the lymph. The spirits that do
not wander would
214. It is noteworthy that labyrinths are mentioned in the above quotation, and that the nodes which transmit lymph are in the form of microscopic networks, the pathways through which must necessarily be of labyrinthine form.
215. We have seen that the lymphatics act as a continuous cleaning system, and it is one which can respond to any increased demand, as in illness, by intensifying its activities. This it does by a great increase in the number of phagocytes and lymphocytes. The action of these cells is as it was before. There are merely more of them, especially of lymphocytes, which will become committed when they meet the antigens associated with the illness. It is clear then that the activities of the cells themselves are the same in health as in recovery from illness. Immunity may even be acquired without an illness intervening, and the body is continually destroying invaders of many kinds before they can do any harm.
216. The possibility of fighting successfully against many toxins and diseases so early that one does not suffer from them suggests that a similar process operates spiritually. In this case, illnesses would correspond to temptations, and immunity without illness supervening would correspond to other means of overcoming falsity and evil. The overcoming of evils and falsities by means which do not include temptation is described in AC 8910. Although it is not said there that the rejection of evils and falsities from the thought before they enter the will is the same as overcoming them without temptation, this must be implied; for if they do not contaminate the will to some extent, the man will not really be suffering temptation. From Divine Providence no. 25, we learn that spiritual fermentations are an alternative to temptations as a means of purification but (lest we should think that temptations are unnecessary) AC 7906 puts the two together, saying that temptations are fermentations in the spiritual sense. The correspondences show that no contradiction is involved, for, as we have said, the normal cleaning process in the body and the recovery from illness are the same, one being merely an intensification of the other
217. Although it seems that fermentations by yeast are the correspondences indicated in DP 25, it is entertaining to observe how closely the language of the Writings about spiritual fermentations describes the defensive actions of the body. We note that "spiritual combats or temptations are fermentations in the spiritual sense, for falsities then desire to conjoin themselves to truths; but truths reject them and at length cast them down as it were…" The activity of the falsities is like that of invading micro-organisms, for these join to themselves (as their own food) various substances in the body. But the organisms are rejected and as it were cast down when the lymphocytes cover them with antibodies. In many cases the process can be watched in a test tube, and the organisms do actually fall to the bottom after the antibody has been added.
218. If the response to an invasion of the body is too slow, the invaders multiply and life is threatened. Such is temptation. Later the defenses may gain the upper hand and immunity may be achieved. Then the invading micro-organisms are inactivated and they are disposed of by the cleaning-up processes. Similarly is a man purified from evil and falsity by temptations which, after he has recovered, leave him immune to attacks of the same kind. These changes cannot but correspond to the agitations and corrections mentioned in AC 5173. (The resemblance between agitations, infestations, and temptations can be deduced from Swedenborg's Index to the Arcana, for AC 7122 appears under Temptations (The Use of Temptations) in the following entry: "Infestations or the temptations of the upright in the other life, take place that evils and falsities, and filthy things, may be removed; and before this they cannot be elevated into heaven, 7122.") The common state of a man passing into the next life with impurities and defilements from his life in the world is very much like the all-too frequent state of the body which is continually harbouring many harmful bacteria (e.g., in the skin, tonsils, nose, throat, gut). The body wages continual warfare against these bacteria without becoming thoroughly immune and casting them out. The agitations in the next life would then correspond to a flare-up during which proper immunity would be achieved.
219. The development of immunity helps one also to realize in part how it can be that the Lord, having overcome the hells by victories in His temptations, should subsequently be in complete control of them. They can no longer assault His Divine Humanity because it is immune. The real reason is because it is Divine, yet the Divine does not work without means, and it may well be that some of the means correspond to the immune reaction.
220. The purification of the blood mentioned in AC 5173 is, of course, done in many ways. The kidneys remove water and many other small molecules. Others that are toxic are modified in the liver, as, for example, alcohol. But the purifications we have in mind in this section deal with infections and toxins that have large molecules. This work is done by the lymph, which flows into the blood stream carrying the lymphocytes which provide the means.
221. This proposition requires elucidating in three steps as follows: (1) Colour is important when it is a characteristic property of a useful substance and not merely adventitious; (2) Haemoglobin is a useful substance, the colour of which indicates important states of the molecule; and (3) The colourlessness of lymph suggests a predominance of wisdom in the functions to which it corresponds, but not of truth only, because it contains many of the constituents of blood.
222. (1.) Colour is important when it is a characteristic
property of a useful substance and not merely adventitious.
223. (2.) Haemoglobin is a useful substance, the
colour of which indicates important states of the molecule.
224. (3.) The colourlessness of lymph suggests a
predominance of wisdom in the functions to which it corresponds, but not
of truth only, because it contains many of the constituents of blood.