The diaphragm forms a partition between the thorax and the abdomen. Its upper side consists of the lower part of the pleura, its lower side of the upper part of the peritoneum. These two membranes come into immediate contact and close union in the central part of the diaphragm, in three spots which are likened to the lobes of a clover leaf; but from this centre there radiate bundles of muscular fibres between the membranes, to the line of attachment at the extremities of the ribs; two large bundles of fibres reach well down the lumbar vertebrae.
When the muscular fibres are relaxed, the diaphragm extends up like a dome into the thorax, lying close to the compressed lungs; and then the liver, and some other organs of the abdomen, lie partly above the line of the ribs in the thorax, and are then in a state of expansion. But when the muscles of the diaphragm contract, they bring down the dome, expand the cavity of the chest, and press the abdominal organs out from it, inducing upon them their turn of contraction.
When the chest is in its state of expansion, it draws in the air from without, and also the fluids of the body from within, sucking upon every vein and lymphatic; and, as the viscera of the abdomen are at the same time compressed, they freely yield up their fluids to the demand of the thorax. And when the thorax contracts, it presses upon arteries, lymphatics, and veins, hastening the departure of the streams ready for the nourishment of the body, and retarding the return currents; and as the abdomen is at that time in a state of expansion, its vessels gladly seize the opportunity to fill themselves full. Liver, spleen, pancreas, kidneys, and even the stomach and intestines depend upon this alternate motion for their power of usefulness; and their common container, the peritoneum, secures this motion to them by uniting itself with the pleura in the diaphragm.
We have, then, on the one side the pleura, loving its trust of serving the heart and the lungs, enjoying the free motion of the lungs. And desiring to extend its delightful animations and on the other hand the peritonĉum, caring for the common wants of the digestive organs, and here desiring to extend its delightful animations;and on the other hand the peritonĉum, caring for the common wants of the digestive organs, and here desiring for them the active life of the lungs, for them and the preparation which that activity ensures to receive the fresh streams of blood from the heart. And these two make a compact to help each other in this common use; and they unite almost as one membrane in the centre of the diaphragm, availing themselves of the assistance of many urgent fibres to bring, their purpose into effect.
Swedenborg's common statement is that the middle heaven includes the body from the neck to the knees but the image seen by Nebuchadnezzar was as to the breast and arms, of silver, as to the belly and thighs of brass, and the legs and feet were of iron. This was a representative of the successive churches, and consequently of the heavens formed from them (AC 10030), and it marks strongly the division between the chest and the abdomen.
Also in TCR 119, he says that the highest heaven is the head, the second is the breast, the lowest is the gastric region, and the church on earth is the loins and feet. Perhaps this last statement refers to the heaven before the Lord's coming, when there was no Christian heaven, and the ancient was imperfectly formed.
Swedenborg says nothing about the angels of this province of the Greatest Man; but their quality is mirrored in the uses of the organ. They are intermediates between the spiritual and the natural heavens, — between the angels whose delight it is to perceive and appropriate spiritual wisdom from the Lord, and to cherish and exercise the love of heavenly uses to the neighbor, and the angels whose duty it is to receive new spirits whose spiritual minds are not yet open, to separate the evil from the good, and to train the good to habits of right thought and action.
These intermediates on the one hand delight in the activity of spiritual thought and affection, and on the other in the use of preparing new angels to receive that thought and affection. Each class loves first its own use, and then that of the other; for the use of each is indispensable to the other. There is no purpose in the action of heart and lungs, unless their influence be received beyond their own province; and there is no satisfaction in preparing spirits to receive the life of heaven, unless heavenly wisdom and love, which constitute that life be abundantly provided. And in order that any use may be accomplished in either domain, there must be submission to the universal law of all created beings, alternate reception and communication, expansion, and contraction; which the lungs, as is becoming to the province of wisdom, perceive most clearly, and by means of the diaphragm impress upon all their associates.
Into this alternation, and thus into the respiration of the heavens, all good spirits are introduced in the province of the lungs (AC 3894); they are continued in it by the animations of the lungs extended to the remotest parts of the body, and the degree of their vitality and usefulness depends upon the degree in which they partake of this animation.
Author: JOHN WORCESTER 1889