"A brief examination of the construction of our bodies from a medical point of view.
1. Now the exact structure of our body each man teaches himself by his experiences of sight and light and perception, having his own nature to instruct him; any one too may learn everything accurately who takes up the researches which those skilled in such matters have worked out in books. And of these writers some learned by dissection the position of our individual organs; others also considered and expounded the reason for the existence of all the parts of the body; so that the knowledge of the human frame which hence results is sufficient for students. But if any one further seeks that the Church should be his teacher on all these points, so that he may not need for anything the voice of those without (for this is the wont of the spiritual sheep, as the Lord says, that they hear not a strange voice), we shall briefly take in hand the account of these matters also.
2. We note concerning our bodily nature three things, for the sake of which our particular parts were formed. Life is the cause of some, good life of others, others again are adapted with a view to the succession of descendants. All things in us which are of such a kind that without them it is not possible that human life should exist, we consider as being in three parts; in the brain, the heart, and the liver. Again, all that are a sort of additional blessings, nature's liberality, whereby she bestows on man the gift of living well, are the organs of sense; for such things do not constitute our life, since even where some of them are wanting man is often none the less in a condition of life; but without these forms of activity it is impossible to enjoy participation in the pleasures of life. The third aim regards the future, and the succession of life. There are also certain other organs besides these, which help, in common with all the others, to subserve the continuance of life, importing by their own means the proper supplies, as the stomach and the lungs, the latter fanning by respiration the fire at the heart, the former introducing the nourishment for the internal organs.
3. Our structure, then, being thus divided, we have carefully to mark that our faculty for life is not supported in any one way by some single organ, but nature, while distributing the means for our existence among several parts, makes the contribution of each individual necessary for the whole; just as the things which nature contrives for the security and beauty of life are also numerous, and differ much among themselves.
4. We ought, however, I think, first to discuss briefly the first beginnings of the things which contribute to the constitution of our life. As for the material of the whole body which serves as a common substratum for the particular members, it may for the present be left without remark; for a discussion as to natural substance in general will not be of any assistance to our purpose with regard to the consideration of the parts.
5. As it is then acknowledged by all that there is in us a share of all that we behold as elements in the universe— of heat and cold, and of the other pair of qualities of moisture and dryness — we must discuss them severally.
6. We see then that the powers which control life are three, of which the first by its heat produces general warmth, the second by its moisture keeps damp that which is warmed, so that the living being is kept in an intermediate condition by the equal balance of the forces exerted by the quality of each of the opposing natures (the moist element not being dried up by excess of heat, nor the hot element quenched by the prevalence of moisture); and the third power by its own agency holds together the separate members in a certain agreement and harmony, connecting them by the ties which it itself furnishes, and sending into them all that self-moving and determining force, on the failure of which the member becomes relaxed and deadened, being left destitute of the determining spirit.
7. Or rather, before dealing with these, it is right that we should mark the skilled workmanship of nature in the actual construction of the body. For as that which is hard and resistent does not admit the action of the senses (as we may see in the instance of our own bones, and in that of plants in the ground, where we remark indeed a certain form of life in that they grow and receive nourishment, yet the resistent character of their substance does not allow them sensation), for this reason it was necessary that some wax-like formation, so to say, should be supplied for the action of the senses, with the faculty of being impressed with the stamp of things capable of striking them, neither becoming confused by excess of moisture (for the impress would not remain in moist substance), nor resisting by extraordinary solidity (for that which is unyielding would not receive any mark from the impressions), but being in a state between softness and hardness, in order that the living being might not be destitute of the fairest of all the operations of nature — I mean the motion of sense.
8. Now as a soft and yielding substance, if it had no assistance from the hard parts, would certainly have, like molluscs, neither motion nor articulation, nature accordingly mingles in the body the hardness of the bones, and uniting these by close connection one to another, and knitting their joints together by means of the sinews, thus plants around them the flesh which receives sensations, furnished with a somewhat harder and more highly-strung surface than it would otherwise have had.
9. While resting, then, the whole weight of the body on this substance of the bones, as on some columns that carry a mass of building, she did not implant the bone undivided through the whole structure: for in that case man would have remained without motion or activity, if he had been so constructed, just like a tree that stands on one spot without either the alternate motion of legs to advance its motion or the service of hands to minister to the conveniences of life: but now we see that she contrived that the instrument should be rendered capable of walking and working by this device, after she had implanted in the body, by the determining spirit which extends through the nerves, the impulse and power for motion. And hence is produced the service of the hands, so varied and multiform, and answering to every thought. Hence are produced, as though by some mechanical contrivance, the turnings of the neck, and the bending and raising of the head, and the action of the chin, and the separation of the eyelids, that takes place with a thought, and the movements of the other joints, by the tightening or relaxation of certain nerves. And the power that extends through these exhibits a sort of independent impulse, working with the spirit of its will by a sort of natural management, in each particular part; but the root of all, and the principle of the motions of the nerves, is found in the nervous tissue that surrounds the brain.
10. We consider, then, that we need not spend more time in inquiring in which of the vital members such a thing resides, when the energy of motion is shown to be here. But that the brain contributes to life in a special degree is shown clearly by the result of the opposite conditions: for if the tissue surrounding it receives any wound or lesion, death immediately follows the injury, nature being unable to endure the hurt even for a moment; just as, when a foundation is withdrawn, the whole building collapses with the part; and that member, from an injury to which the destruction of the whole living being clearly follows, may properly be acknowledged to contain the cause of life.
11. But as furthermore in those who have ceased to live, when the heat that is implanted in our nature is quenched, that which has become dead grows cold, we hence recognize the vital cause also in heat: for we must of necessity acknowledge that the living being subsists by the presence of that, which failing, the condition of death supervenes. And of such a force we understand the heart to be as it were the fountain-head and principle, as from it pipe-like passages, growing one from another in many ramifications, diffuse in the whole body the warm and fiery spirit.
12. And since some nourishment must needs also be provided by nature for the element of heat — for it is not possible that the fire should last by itself, without being nourished by its proper food — therefore the channels of the blood, issuing from the liver as from a fountainhead, accompany the warm spirit everywhere in its way throughout the body, that the one may not by isolation from the other become a disease and destroy the constitution. Let this instruct those who go beyond the bounds of fairness, as they learn from nature that covetousness is a disease that breeds destruction.
13. But since the Divinity alone is free from needs, while human poverty requires external aid for its own subsistence, nature therefore, in addition to those three powers by which we said that the whole body is regulated, brings in imported matter from without, introducing by different entrances that which is suitable to those powers.
14. For to the fount of the blood, which is the liver, she furnishes its supply by food: for that which from time to time is imported in this way prepares the springs of blood to issue from the liver, as the snow on the mountain by its own moisture increases the springs in the low ground, forcing its own fluid deep down to the veins below.
15. The breath in the heart is supplied by means of the neighbouring organ, which is called the lungs, and is a receptacle for air, drawing the breath from without through the windpipe inserted in it, which extends to the mouth. The heart being placed in the midst of this organ (and itself also moving incessantly in imitation of the action of the ever-moving fire), draws to itself, somewhat as the bellows do in the forges, a supply from the adjacent air, filling its recesses by dilatation, and while it fans its own fiery element, breathes upon the adjoining tubes; and this it does not cease to do, drawing the external air into its own recesses by dilatation, and by compression infusing the air from itself into the tubes.
16. And this seems to me to be the cause of this spontaneous respiration of ours; for often the mind is occupied in discourse with others, or is entirely quiescent when the body is relaxed in sleep, but the respiration of air does not cease, though the will gives no co-operation to this end. Now I suppose, since the heart is surrounded by the lungs, and in the back part of its own structure is attached to them, moving that organ by its own dilatations and compressions, that the inhaling and exhaling of the air is brought about by the lungs: for as they are a lightly built and porous body, and have all their recesses opening at the base of the windpipe, when they contract and are compressed they necessarily force out by pressure the air that is left in their cavities; and, when they expand and open, draw the air, by their distention, into the void by suction.
17. This then is the cause of this involuntary respiration — the impossibility that the fiery element should remain at rest: for as the operation of motion is proper to heat, and we understand that the principle of heat is to be found in the heart, the continual motion going on in this organ produces the incessant inspiration and exhalation of the air through the lungs: wherefore also when the fiery element is unnaturally augmented, the breathing of those fevered subjects becomes more rapid, as though the heart were endeavouring to quench the flame implanted in it by more violent breathing.
18. But since our nature is poor and in need of supplies for its own maintenance from all quarters, it not only lacks air of its own, and the breath which excites heat, which it imports from without for the preservation of the living being, but the nourishment it finds to fill out the proportions of the body is an importation. Accordingly, it supplies the deficiency by food and drink, implanting in the body a certain faculty for appropriating that which it requires, and rejecting that which is superfluous, and for this purpose too the fire of the heart gives nature no small assistance.
19. For since, according to the account we have given, the heart which kindles by its warm breath the individual parts, is the most important of the vital organs, our Maker caused it to be operative with its efficacious power at all points, that no part of it might be left ineffectual or unprofitable for the regulation of the whole organism. Behind, therefore, it enters the lungs, and, by its continuous motion, drawing that organ to itself, it expands the passages to inhale the air, and compressing them again it brings about the exspiration of the imprisoned air; while in front, attached to the space at the upper extremity of the stomach, it warms it and makes it respond by motion to its own activity, rousing it, not to inhale air, but to receive its appropriate food: for the entrances for breath and food are near one another, extending lengthwise one alongside the other, and are terminated in their upper extremity by the same boundary, so that their mouths are contiguous and the passages come to an end together in one mouth, from which the entrance of food is effected through the one, and that of the breath through the other.
20. Internally, however, the closeness of the connection of the passages is not maintained throughout; for the heart intervening between the base of the two, infuses in the one the powers for respiration, and in the other for nutriment. Now the fiery element is naturally inclined to seek for the material which serves as fuel, and this necessarily happens with regard to the receptacle of nourishment; for the more it becomes penetrated by fire through the neighbouring warmth, the more it draws to itself what nourishes the heat. And this sort of impulse we call appetite.
21. But if the organ which contains the food should obtain sufficient material, not even so does the activity of the fire become quiescent: but it produces a sort of melting of the material just as in a foundry, and, dissolving the solids, pours them out and transfers them, as it were from a funnel, to the neighbouring passages: then separating the coarser from the pure substance, it passes the fine part through certain channels to the entrance of the liver, and expels the sedimentary matter of the food to the wider passages of the bowels, and by turning it over in their manifold windings retains the food for a time in the intestines, lest if it were easily got rid of by a straight passage it might at once excite the animal again to appetite, and man, like the race of irrational animals, might never cease from this sort of occupation.
22. As we saw, however, that the liver has special need of the co-operation of heat for the conversion of the fluids into blood, while this organ is in position distant from the heart (for it would, I imagine, have been impossible that, being one principle or root of the vital power, it should not be hampered by vicinity with another such principle), in order that the system may suffer no injury by the distance at which the heat-giving substance is placed, a muscular passage (and this, by those skilled in such matters, is called the artery) receives the heated air from the heart and conveys it to the liver, making its opening there somewhere beside the point at which the fluids enter, and, as it warms the moist substance by its heat, blends with the liquid something akin to fire, and makes the blood appear red with the fiery tint it produces.
23. Issuing thence again, certain twin channels, each enclosing its own current like a pipe, disperse air and blood (that the liquid substance may have free course when accompanied and lightened by the motion of the heated substance) in various directions over the whole body, breaking at every part into countless branching channels; while as the two principles of the vital powers mingle together (that alike which disperses heat, and that which supplies moisture to all parts of the body), they make, as it were, a sort of compulsory contribution from the substance with which they deal to the supreme force in the vital economy.
24. Now this force is that which is considered as residing in the cerebral membranes and the brain, from which it comes that every movement of a joint, every contraction of the muscles, every spontaneous influence that is exerted upon the individual members, renders our earthen statue active and mobile as though by some mechanism. For the most pure form of heat and the most subtle form of liquid, being united by their respective forces through a process of mixture and combination, nourish and sustain by their moisture the brain, and hence in turn, being rarefied to the most pure condition, the exhalation that proceeds from that organ anoints the membrane which encloses the brain, which, reaching from above downwards like a pipe, extending through the successive vertebræ, is (itself and the marrow which is contained in it) conterminous with the base of the spine, itself giving like a charioteer the impulse and power to all the meeting-points of bones and joints, and to the branches of the muscles, for the motion or rest of the particular parts.
25. For this cause too it seems to me that it has been granted a more secure defense, being distinguished, in the head, by a double shelter of bones round about, and in the vertebræ of the neck by the bulwarks formed by the projections of the spine as well as by the diversified interlacings of the very form of those vertebræ, by which it is kept in freedom from all harm, enjoying safety by the defense that surrounds it.
26. So too one might suppose of the heart, that it is itself like some safe house fitted with the most solid defences, fortified by the enclosing walls of the bones round about; for in rear there is the spine, strengthened on either side by the shoulder-blades, and on each flank the enfolding position of the ribs makes that which is in the midst between them difficult to injure; while in front the breast-bone and the juncture of the collar-bone serve as a defense, that its safety may be guarded at all points from external causes of danger.
27. As we see in husbandry, when the rain fall from the clouds or the overflow from the river channels causes the land beneath it to be saturated with moisture (let us suppose for our argument a garden, nourishing within its own compass countless varieties of trees, and all the forms of plants that grow from the ground, and whereof we contemplate the figure, quality, and individuality in great variety of detail); then, as these are nourished by the liquid element while they are in one spot, the power which supplies moisture to each individual among them is one in nature; but the individuality of the plants so nourished changes the liquid element into different qualities; for the same substance becomes bitter in wormwood, and is changed into a deadly juice in hemlock, and becomes different in different other plants, in saffron, in balsam, in the poppy: for in one it becomes hot, in another cold, in another it obtains the middle quality: and in laurel and mastick it is scented, and in the fig and the pear it is sweetened, and by passing through the vine it is turned into the grape and into wine; while the juice of the apple, the redness of the rose, the radiance of the lily, the blue of the violet, the purple of the hyacinthine dye, and all that we behold in the earth, arise from one and the same moisture, and are separated into so many varieties in respect of figure and aspect and quality; the same sort of wonder is wrought in the animated soil of our being by Nature, or rather by Nature's Lord. Bones, cartilages, veins, arteries, nerves, ligatures, flesh, skin, fat, hair, glands, nails, eyes, nostrils, ears — all such things as these, and countless others in addition, while separated from one another by various peculiarities, are nourished by the one form of nourishment in ways proper to their own nature, in the sense that the nourishment, when it is brought into close relation with any of the subjects, is also changed according to that to which it approaches, and becomes adapted and allied to the special nature of the part. For if it should be in the neighbourhood of the eye, it blends with the visual part and is appropriately distributed by the difference of the coats round the eye, among the single parts; or, if it flow to the auditory parts, it is mingled with the auscultatory nature, or if it is in the lip, it becomes lip; and it grows solid in bone, and grows soft in marrow, and is made tense with the sinew, and extended with the surface, and passes into the nails, and is fined down for the growth of the hair, by correspondent exhalations, producing hair that is somewhat curly or wavy if it makes its way through winding passages, while, if the course of the exhalations that go to form the hair lies straight, it renders the hair stiff and straight.
28. Our argument, however, has wandered far from its purpose, going deep into the works of nature, and endeavouring to describe how and from what materials our particular organs are formed, those, I mean, intended for life and for good life, and any other class which we included with these in our first division.
29. For our purpose was to show that the seminal cause of our constitution is neither a soul without body, nor a body without soul, but that, from animated and living bodies, it is generated at the first as a living and animate being, and that our humanity takes it and cherishes it like a nursling with the resources she herself possesses, and it thus grows on both sides and makes its growth manifest correspondingly in either part:— for it at once displays, by this artificial and scientific process of formation, the power of soul that is interwoven in it, appearing at first somewhat obscurely, but afterwards increasing in radiance concurrently with the perfecting of the work.
30. And as we may see with stone-carvers — for the artist's purpose is to produce in stone the figure of some animal; and with this in his mind, he first severs the stone from its kindred matter, and then, by chipping away the superfluous parts of it, advances somehow by the intermediate step of his first outline to the imitation which he has in his purpose, so that even an unskilled observer may, by what he sees, conjecture the aim of his art; again, by working at it, he brings it more nearly to the semblance of the object he has in view; lastly, producing in the material the perfect and finished figure, he brings his art to its conclusion, and that which a little before was a shapeless stone is a lion, or a man, or whatsoever it may be that the artist has made, not by the change of the material into the figure, but by the figure being wrought upon the material. If one supposes the like in the case of the soul he is not far from probability; for we say that Nature, the all-contriving, takes from its kindred matter the part that comes from the man, and moulds her statue within herself. And as the form follows upon the gradual working of the stone, at first somewhat indistinct, but more perfect after the completion of the work, so too in the moulding of its instrument the form of the soul is expressed in the substratum, incompletely in that which is still incomplete, perfect in that which is perfect; indeed it would have been perfect from the beginning had our nature not been maimed by evil. Thus our community in that generation which is subject to passion and of animal nature, brings it about that the Divine image does not at once shine forth at our formation, but brings man to perfection by a certain method and sequence, through those attributes of the soul which are material, and belong rather to the animal creation.
31. Some such doctrine as this the great apostle also teaches us in his Epistle to the Corinthians, when he says, When I was a child, I spoke as a child, I understood as a child, I thought as a child; but when I became a man I put away childish things 1 Corinthians 13:11; not that the soul which arises in the man is different from that which we know to be in the boy, and the childish intellect fails while the manly intellect takes its being in us; but that the same soul displays its imperfect condition in the one, its perfect state in the other.
32. For we say that those things are alive which spring up and grow, and no one would deny that all things that participate in life and natural motion are animate, yet at the same time one cannot say that such life partakes of a perfect soul — for though a certain animate operation exists in plants, it does not attain to the motions of sense; and on the other hand, though a certain further animate power exists in the brutes, neither does this attain perfection, since it does not contain in itself the grace of reason and intelligence.
33. And even so we say that the true and perfect soul is the human soul, recognized by every operation; and anything else that shares in life we call animate by a sort of customary misuse of language, because in these cases the soul does not exist in a perfect condition, but only certain parts of the operation of the soul, which in man also (according to Moses' mystical account of man's origin) we learn to have accrued when he made himself like this sensuous world. Thus Paul, advising those who were able to hear him to lay hold on perfection, indicates also the mode in which they may attain that object, telling them that they must put off the old man, and put on the man which is renewed after the image of Him that created him Colossians 3:9-10.
34. Now may we all return to that Divine grace in which God at the first created man, when He said, Let us make man in our image and likeness; to Whom be glory and might for ever and ever. Amen."