THE NATURAL BASIS
CORRESPONDENCES OF THE EYE
356. Sight is such a remarkable faculty that whole volumes would
be needed to do it justice. The more one learns about it, the better one
sees how well it corresponds to the understanding. Knowing, understanding,
and being wise are such a large part of life that we are not surprised
to find that eighty percent of all learning involves the organs that correspond
to the understanding. This is among the many things that we have been told
in Dr. Allen's papers on "Sight, the Visual Process and Doctrine" (The
New Philosophy, 1981, pp. 26-35 and 1982, pp. 138-147. See also 1980, pp.
72-74.). These papers have been included as an appendix by the kind permission
of Dr. Allen. The reader is urged to study them. He will be amazed, and
delighted by the wide extent of the correspondences presented, including
those parts of the brain concerned with sight.
357. Some of the most delightful and joyous passages of the Writings
are devoted to descriptions of the correspondences of the eye. In order
to appreciate their quality one needs to read them in full, but for our
present purposes a few brief extracts must suffice. The province of the
eye includes the heaven of little children where there are delightful gardens
(HH 332, 333, and 337). Those who relate to the coats of the eye communicate
with the heavens where truths and goods are represented by a paradise and
a city. There are, as Dr. Allen also points out, three coats of the eye.
The outer coat is continuous with the dura mater, the spirits of which
are in relative obscurity (see Nos. 278-282 above) but, as we see, they
communicate with the heavens. Those who belong to the provinces of the
inner layers will obviously communicate more nearly. Such may have been
the person mentioned in AC 4412, who presented beautiful and delightful
representatives related to the eye. We are told
358. Here we consider briefly smell, hearing, and taste. In trying to understand what is said about the sense of smell, it is important to bear in mind that it is related to perception. The scene depicted in relation to those who correspond to the exteriors of the nostrils is not particularly attractive. The societies there need protection by angelic choirs from dull and stupid spirits who are represented by mucus (AC 4627). Nevertheless a comparison of AC 4624 and AC 4627 shows that the persons in this province are in the Grand Man and that, although they are said to correspond to the exteriors of the nostrils (by which one might have understood only the visible part of the nose), they also correspond to the sense of smell.
359. More pleasant things are related of those who correspond to the interiors and internals of the nostrils, such as bright and variegated lights and a warm atmosphere like that of early summer. But they are mentioned only very briefly and one is left with a feeling that the state here is less glorious than that in the province of the eyes. However, the brief description and the resulting feeling may well be due to the state in the province of the nostrils being relatively remote from our present style of thought, since we now use the understanding more and perception less than did the MAC. We may therefore be unwilling to think of the state of those in the province of the interiors of the nostrils as being inferior and merely note that it is different. Correspondences of the sense of smell are examined further in a later chapter.
360. On turning to the sense of hearing we find that we are told but little concerning those who correspond to the external ear. Perhaps this is because they are simple and merely obedient, a state in which there is little life (AC 4656) and therefore little of interest.
361. As matters related to the ear become more internal, the mental sight (or understanding) becomes involved. Certain parts of the Arcana (AC 4653-4658) seem to show that as the spiritual relationships of the ear tend towards internal things they tend towards sight. By correspondence, this would mean that if obedience is to have a genuine internal it must be from understanding. This is confirmed in AC 3869 and also where it is said "the things that enter by the sense of hearing enter into the understanding and at the same time into the will; therefore the hearing signifies perception and obedience" (AE 14). The understanding in this context must therefore be that special quality of enlightened understanding which is called perception, as we also read in several places (e.g., AR 87). Such enlightenment is a blessing enjoyed by celestial angels whose wisdom is beyond our grasp. There is, however, plenty for us to learn at the lower level where the province of the ear is constituted by those who are called obediences (AC 4653). A more detailed study will be undertaken in Chapter XV. Meanwhile, it is sufficient to note that in the accounts in AC we find little or no representation of heavenly things although the wisdom itself is clearly of heaven.
362. Concerning taste, we are shown very clearly the devastation that occurs when it is depraved, but comparatively little is said about its correspondence when it is in order; only that it corresponds to the perception and to the affection of spiritual food.
363. Faith is referred to in the story of Cain when a mark was set upon
him to prevent anyone from killing him. The internal sense of this was
that violence should not be done to faith because it was going to become
the means of salvation. Faith at that time was acquired through hearing
and was probably merely obeyed and not understood by most of those who
received it. Yet, in time, understanding was to grow (just as hearing tends
to sight as it gets more internal) (See n. 373 below). Thus the understanding
also was to be inviolable, as we read in many places where it is pointed
out that even with the evil the understanding can be elevated into heavenly
light (e.g. DLW 416 et. seq., AC 9399). Here we see the special quality
of faith and hence of the understanding where faith lives; it seems fitting
that the representation of these things, i.e., the correspondences of sight,
should be specially beautiful and glorious. These considerations, however,
are only general and introductory. They
364. We read in AC 4407, "The eye is the noblest organ of the face, and communicates more directly with the understanding than the rest of the organs of sense…the sight penetrates to the internal sensory, which is in the brain, by a shorter and more interior way than the speech perceived by the ear." This statement may seem difficult to understand, for the eye is at the front of the head, and that part of the cerebral cortex which deals with vision (presumably "the internal sensory") is at the back. So the eye and its internal sensory are as far apart as they can be. How can they communicate by a shorter way? What is "a more interior way"? An attempt to answer such questions could be made by considering all the anatomical and physiological qualities known to us that make the eye so special. See Figure 20. Obviously there are many of them, but there is one in particular which is the natural centre and cause of the rest. Knowledge that is now available enables us to go a step further than could safely have been indicated in the Writings, for we can now say that the eye is, as it were, the brain itself responding to light. The other senses serve the brain, but they are not themselves the brain. Certainly several parts of the eye are not the brain, but the retina, the optic nerve, and to some extent the vitreous body are more truly represented as a part of the brain than as any other tissue. Thus the eye shares with the brain a more exalted status than any other organ.
A diagrammatic representation of the connections between the retinae and the visual cortex. The nerve fibres from half of each retina cross over to the opposite side so that each side of the brain sees through both eyes. As the brain is seen from below, its right side is on the left of the drawing. The optic chiasma is also shown in Figure 16, but here in Figure 20 the nerves are enlarged and spaced out for clarity. As is clear from Figure 16, the optic tract is quite a normal sized compact bundle of nerves. Since the lens of the eye reverses the image, the left fields of view (not quite identical for stereoscopic vision) are on the right side of each retina, and each right half-retina communicates with the right occipital lobe.
In the early stages of the embryo, when it is very small the brain is a hollow tube. At one spot on each side a circular area begins to appear. Figure 21a shows a section of the embryo across these two points from which it can be seen that the circular area is due to an outgrowth of the primitive brain resulting in a slight swelling or extension of the delicate skin or ectoderm. Subsequent stages are shown in diagrams b to h, drawn on a larger scale. In c the retina is beginning to take its hollowed shape and the ectoderm to form the lens pit. By h, the pigmented layer and the nervous layer of the retina have come together.
365. Although it is not necessary to justify a view generally accepted by anatomists, some readers may be interested in the evidence, which is asfollows:
1. The eye begins as a small pit or dent in the side of the brain of the embryo very early in its development. Thhe pit is soon covered by another layer that forms the lens, and the brain cells lining the pit become the retina which is thus a part of the brain from its first moment of differentiation. The ensuing formation of the optic nerve is merely a lengthening of nerve cells in the retina still within their own milieu of the brain. T1. The eye begins as a small pit or dent in the side of the brain of the embryo very early in its development. The pit is soon covered by another he development of other sense organs follows a different course and they are linked to the brain by the subsequent growth of nerve fibres. Figure 21 illustrates the stages in the development of the eye.366. Knowledge of the eye as part of the brain, or the retina as a little brain, lends special interest to the following statement from AC 4407:
Hence also it is that certain animals, being destitute of understanding, have, as it were, two subsidiary brains within the orbits of their eyes, for their intellectual depends on their sight. But with man this is not the case, for he enjoys the use of an ample brain.As in innumerable other instances the structure of man's body has much in common with those of animals, and, as we have just seen, he also has subsidiary brains within his eyes. The phrase "with man this is not the case" means that his intellectual does not depend on his sight. But the little brains within the eyes must be of use to carry out some preliminary processing of sense impressions in order to leave the main brain more capacity and freedom for intellectual response and rule.
367. Having shown that the eye, unlike other organs, is itself part of the brain, we can conclude that the image on the retina is already in the brain and therefore the pathway conducting information from the retina to the internal sensory must be more interior than others.
368. None of the myriad nerves sending information from the head and body towards the cerebral cortex makes direct contact with the cortex. Every nerve ends in one or more relay stations in the spinal cord or in the brain. Here each fibre passes its impulses on to one or many other nerve cells. There are many relay stations and most of them have several (or many) other functions such as, for example, inhibition, excitation, integration and interaction between incoming impulses from sense organs and out-going (controlling) impulses from the central area or cerebral cortex. Some sense organs, e.g., those of touch, can even be instructed to respond to different stimuli, e.g., warmth instead of pressure (See also No. 346).
369. The pathway for sight may be described very briefly as follows. The optic nerves from both eyes come together in the optic chiasma near the centre of the base of the brain, and then diverge again. In the chiasma about half the fibres from each eye cross over to the opposite side. Since it is only about half, there is no difficulty in each eye having the same sort of correspondences as the same side of the brain. Moreover, each side of the brain sees through both eyes, the right side using the right halves of both retinae. From the chiasma, nearly all the fibres continue to the lateral geniculate body which is the one relay station whence new nerve fibres radiate to the visual cortex. The few fibres which do not connect the retina with the lateral geniculate body send impulses via a different relay back to the iris for adjustment according to light intensity (a typical reflex).
370. The path of the nerves for hearing is more complicated. Some impulses reach the auditory part of the cerebral cortex through as few as three relay stations. Others may pass through as many as five, besides extra ones involved in several places where some (N.B. not all!) of the fibres cross from one side of the brain to the other.
372. The anatomical facts adduced above serve to show that, although some of the statements in AC 4407 might be difficult to accept at first, a quite brief excursion into the anatomy as now known shows them to be correct in a way that was not known, and could not have been understood or accepted when they were written.
373. Words spoken to us are often translated first into visual memories before being submitted to the understanding. Thus, on receipt of a command, e.g., "Thou shalt not eat of it," we first make a picture of the things mentioned, e.g., a fruit tree. This explains the use of the phrase "sight of the interior hearing" (AC 4653:2). It is confirmed in other places, e.g., "what is heard passes into the internal sight which is that of the understanding." (AC 83611, and 9311). These things do not detract from the neurological correspondences. They are part of the same phenomenon.
374. The eminent quality of the eye has now been sufficiently established, and the relationship between the anatomical facts and the beauty of the representations seen in the province of the eye will now be clear. The eye is brain. The brain is heaven. When we discussed the heavenly form of the brain (Nos. 273-277) we saw how fugacious is knowledge of the heavenly form. Here, however, where correspondences of the eye are the subject, we have delightful things that we can even now appreciate. Such correspondences are not related of the brain itself. This is perhaps because, as we are repeatedly told, its inner form is beyond our comprehension. The eye provides an eminent substitute, being still of the brain, but a little removed.