In this description, we shall take a man as our point of departure. As he lives on the earth, man at present consists of the physical body, the ether or life body, the astral body, and the "I." This fourfold human nature has in itself the dispositions for a higher development. The "I" by its initiative transforms the "lower" bodies, and thereby incorporates into them higher parts of human nature.

The ennobling and purifying of the astral body by the "I" causes the development of the "spirit self" (Manas), the transformation of the ether or life body creates the life spirit (Buddhi), and the transformation of the physical body creates the true "spirit man" (Atma).

The transformation of the astral body is in full progress in the present period of the development of the earth; the conscious transformation of the ether body and of the physical body belongs to later times; at present it has begun only among the initiates - those trained in the science of the spirit and their pupils. This threefold transformation of man is a conscious one; it was preceded by one more or less unconscious during the previous development of the earth. It is in this unconscious transformation of astral body, ether body, and physical body that one must seek the origin of the sentient soul, of the intellectual soul, and of the consciousness soul.

One must now make clear to oneself which one of the three bodies of man (the physical, the ether, and the astral body) is in its way most perfect. One can easily be tempted to consider the physical body as the lowest and therefore as the least perfect. However, in this, one would be in error. It is true that the astral body and the ether body will attain a high degree of perfection in the future, but at present the physical body is more perfect in its way than are they in theirs.

Only because man has this physical body in common with the lowest natural realm on earth, the mineral realm, is it possible for the error we have mentioned to arise. For man has the ether body in common with the higher plant realm, and the astral body with the animal realm. Now it is true that the physical body of man is composed of the same substances and forces which exist in the wider mineral realm, but the manner in which these substances and forces interact in the human body is the expression of wisdom and perfection in the structure. One will soon convince himself of the truth of this statement if he undertakes to study this structure not merely with the dry intellect but with his whole feeling soul. One can take any part of the human physical body as the subject for this contemplation, for instance the highest part of the upper thigh bone. This is not an amorphous massing of substance, but rather is joined together in the most artful manner, out of diminutive beams which run in different directions. No modern engineering skill could fit a bridge or something similar together with such wisdom. Today such things are still beyond the reach of the most perfect human wisdom.

The bone is constructed in this wise fashion so that, through the arrangement of the small beams, the necessary carrying capacity for the support of the human torso can be attained with the least amount of substance. The least amount of matter is used in order to achieve the greatest possible effect in terms of force. In face of such a "masterwork of natural architecture," one can only become lost in admiration. No less can one admire the miraculous structure of the human brain or heart, or of the totality of the human physical body. One should compare with it the degree of perfection which for example the astral body has attained at the present stage of development of mankind.

The astral body is a carrier of pleasure and distaste, of the passions, impulses and desires and so forth. But what attacks this astral body perpetrates against the wise arrangement of the physical body! A large part of the stimulants which man consumes are poisons for the heart. From this it can be seen that the activity which produces the physical structure of the heart proceeds in a wiser manner than the activity of the astral body, which even runs counter to this wisdom. It is true that in future the astral body will advance to higher wisdom; at present, however, it is not as perfect in its way as is the physical body. Something similar could be shown to be true for the ether body, and also for the "I," that being which, from moment to moment, must struggle gropingly toward wisdom through error and illusion.

If one compares the levels of perfection of the parts of the human being, one will easily discover that at present the physical body is in its way the most perfect, that the ether body is less perfect, the astral body still less, and that in its way the least perfect part of man at present is the "I." This is due to the fact that in the course of the planetary development of the human dwelling-place the physical body of man has been worked on the longest. What man today carries as his physical body has lived through all the developmental stages of Saturn, Sun, Moon, and earth, up to the present stage of the latter. All the forces of these planetary bodies have successively worked on this body, so that gradually it has been able to attain its present degree of perfection. It is thus the oldest part of the present-day human entity.

The ether body, as it now appears in man, did not exist at all during the Saturn period. It was only added during the Sun development. Hence the forces of four planetary bodes have not worked on it as on the physical body, but only those of three, namely, of Sun, Moon, and earth. Therefore only in a future period of development can it become as perfect in its way as is the physical body at present. The astral body joined the physical body and the ether body only during the Moon period, and the "I" did so only during the earth period.

One must represent to oneself that the physical human body attained a certain stage of its development on Saturn, and that this development was carried forward on the Sun in such a way that from that time on the physical body could become the carrier of an ether body. On Saturn this physical body had attained a point where it was an extremely complex mechanism, which however had nothing in it of life.

The complicatedness of its structure finally caused it to disintegrate. For this complicatedness had reached such a degree that this physical body could no longer maintain itself by means of the merely mineral forces which were acting in it. It was through this collapse of the human bodies that the decline of Saturn was brought about. Of the present natural realms, namely the mineral realm, the plant realm, the animal realm, and the human realm, Saturn had only the last-named. What one knows today as animals, plants, and minerals did not yet exist on Saturn. Of the present four natural realms, there existed on this heavenly body only man in his physical body, and this physical body was in fact a kind of complicated mineral. The other realms came into existence because not all beings could attain full development on the successive heavenly bodies.

Thus only a part of the human bodies developed on Saturn attained the full Saturn goal. Those human bodies which did attain this goal were awakened, so to speak, to a new existence in their old form during the Sun period, and this form was permeated with the ether body. They thereby developed to a higher level of perfection. They became a kind of plant men. That portion of the human bodies however which had not been able to attain the full goal of development on Saturn had to continue during the Sun period what they had previously not completed, but under considerably more unfavorable conditions than those which existed for this development on Saturn. They therefore fell behind the portion which had attained the full goal on Saturn. Thus on the Sun another natural realm came into being in addition to the human realm.

It would be erroneous to believe that all the organs in the present-day human body already began to be developed on Saturn. This is not the case. Rather it is particularly the sensory organs in the human body which have their origin in this ancient time. It is the first rudiments of eyes, ears and so forth which have such an early origin, rudiments which formed on Saturn in somewhat the same way that "lifeless crystals" now form on earth; the corresponding organs then attained their present form by again and again transforming themselves in the direction of greater perfection in each of the succeeding planetary periods. On Saturn they were physical instruments, and nothing else.
On the Sun they were transformed, because an ether or life body permeated them. They were thereby brought into the life process. They became animated physical instruments. To them were added those parts of the human physical body which cannot develop at all except under the influence of an ether body: the organs of growth, of nourishment, and of reproduction. Of course the first rudiments of these organs, as they developed on the Sun, again do not resemble in perfection the form which they have at present.

The highest organs which the human body at that time acquired through the interaction of physical body and ether body were those which at present have developed into the glands. The physical human body on the Sun is thus a system of glands, on which sensory organs of a corresponding level of development are impressed.

The development continued on the Moon. To the physical body and the ether body is added the astral body. Thereby the first rudiment of a nervous system is integrated into the glandular sensory body. One can see that the physical human body becomes more and more complicated in the successive planetary development periods. On the Moon it is composed of nerves, glands, and senses. The senses have behind them a two-fold process of transformation and perfection, while the nerves are at their first stage. If one looks at the Moon man as a whole, he consists of three parts: a physical body, an ether body, and an astral body. The physical body is tripartite; its partition is the result of the work of the Saturn, Sun, and Moon forces. The ether body is only bipartite. It has in itself only the effect of the work of Sun and Moon, and the astral body is still unipartite. Only the Moon forces have worked on it.

Through the absorption of the astral body on the Moon, man has become capable of a life of sensation, of a certain inwardness. Within his astral body he can form images of what takes place in his environment. These images in a certain respect are to be compared with the dream images of present-day human consciousness, but they are more vivid and colorful, and, most important, they relate to events in the outside world, while present-day dream images are mere echoes of daily life or are otherwise unclear mirrorings of inner or outer events. The images of the Moon consciousness corresponded completely to whatever they were related to externally.

Assume for instance that a Moon man as he has just been characterized, consisting of physical body, ether body, and astral body, had approached another Moon being. It is true that he could not have perceived the latter as a spatial object, for this has become possible only in the earth consciousness of man; but within his astral body would have arisen an image which in its color and shape would have quite exactly expressed whether the other being was well or ill disposed toward this Moon man, whether it would be useful or dangerous to him. As a result, the Moon man could regulate his behavior entirely in accordance with the images which arose in his image consciousness, These images were a complete means of orientation for him. The physical instrument which the astral body needed in order to enter into relation with the lower natural realms was the nervous system, integrated into the physical body.

In order that the transformation of man described here could occur during the Moon period, the assistance of a great universal event was needed. The integration of the astral body and the related development of a nervous system in the physical body was only made possible by the fact that what had previously been one body, the Sun, split into two - into Sun and Moon.

The former advanced to the state of a fixed star, the latter remained a planet - which the Sun also had been - and began to circle around the Sun, from which it had split off. Through this a significant transformation took place in everything which lived on Sun and Moon. Here for the moment we shall follow this process of transformation only insofar as it concerns the life of the Moon. Man, consisting of physical body and astral body, had remained united with the Moon when it split off from the Sun. He thereby entered into entirely new conditions of existence. For the Moon took with it only a part of the forces contained in the Sun, and this part now acted on man from his own heavenly body; the Sun had retained the other part of the forces within itself. This latter part is now sent from the outside to the Moon and hence also to its inhabitant, man.
If the previous relationship had remained in existence, if all the Sun forces had continued to reach man from his own scene of activity, that inner life which shows itself in the arising of the images of the astral body could not have developed. The Sun force continued its activity on the physical body and ether body from the outside; it had already acted on both of these previously. But it liberated a portion of these two bodies for influences which emanated from the Moon, the heavenly body newly created by a splitting-off. Thus, on the Moon man was under a two-fold influence, that of the Sun and that of the Moon. It is to be ascribed to the influence of the Moon that out of the physical and the ether body there developed those parts which permitted the imprinting of the astral body. An astral body can only create images when the Sun forces reach it from outside rather than from its own planet. The Moon influences transformed the sensory rudiments and the glandular organs in such a way that a nervous system could be integrated into them; and the sun influences brought it about that the images for which this nervous system was the instrument corresponded to the external Moon events in the manner described above.

The development could only progress to a certain point in this manner. Had this point been overstepped, the Moon man would have become hardened in his inner life of images, and thereby he would have lost all connection with the Sun. When the time had come, the Sun again absorbed the Moon, so that again for some time both were one body. The union lasted until man was far enough advanced so that his hardening, which would have had to take place on the Moon, could be prevented by a new stage of development. When this had occurred a new separation took place, but this time the Moon took Sun forces along with itself which previously it had not received.

Through this it came about that another separation took place after some time. What had last split off from the Sun was a heavenly body which contained all the forces and beings at present living on earth and moon. Thus the earth still contained within itself the moon which now circles around it. If the latter had remained within it, it could never have become the scene of any human development, including the present one. The forces of the present moon first had to be cast off, and man had to remain on the thus purified earthly scene and continue his development there. In this way three heavenly bodies developed out of the old Sun. The forces of two of these heavenly bodies, the new sun and the new moon, are sent to the earth and hence to its inhabitant from the outside.

Through this progress in the development of the heavenly bodies it became possible that into the tripartite human nature, as it still had been on the Moon, the fourth part, the "I," integrated itself. This integration was connected with a perfecting of the physical body, the ether body, and the astral body. The perfecting of the physical body consisted in that the system of the heart was incorporated in it as the preparer of warm blood. Of course, now the sensory system, the glandular system, and the nervous system had to be transformed in such a way that in the human organism they would be compatible with the newly added system of the warm blood. The sensory organs were so transformed that out of the mere image consciousness of the old Moon the object consciousness could develop, which makes possible the perception of external objects, and which man at present possesses from the time he awakes in the morning until he falls asleep in the evening.

On the old Moon the senses were not yet open to the outside; the images of consciousness arose from within, and just this opening of the senses to the external is the achievement of the earth development. It has been stated above that not all of the human bodies formed on Saturn attained the goal which was set for them there, and that on the Sun, alongside the human realm in its form of that time, a second natural realm developed. One must realize that at each of the subsequent stages of development, on Sun, Moon, and earth, there were always beings which fell short of their goals and that through this the lower natural realms came into existence. The animal realm, which is closest to man, had already fallen behind on Saturn, but partially made up the development under unfavorable conditions on Sun and Moon, so that while on the earth it was not as far advanced as man, in part it still had the capacity to receive warm blood as he did. For warm blood existed in none of the natural realms before the period of earth.

The present-day cold-blooded (or variably warm) animals and certain plants came into existence because certain beings of the lower Sun realm again fell short of the stage which the other beings of this realm attained. The present-day mineral realm came into existence last, in fact only during the earth period.

The fourfold man of earth receives from sun and moon the influences of those forces which have remained connected with these heavenly bodies. From the sun those forces reach him which further progress, growth, and becoming; from the moon come the hardening, forming forces. If man stood only under the influence of the sun he would dissolve in an immeasurably rapid process of growth It is for this reason that formerly, after an appropriate time, he had to leave the Sun and to receive a retarding of his over-rapid progress on the split-off old Moon. But if then he had remained permanently connected with the latter, this retarding of his growth would have hardened him in a rigid form. Therefore he advanced to the development of earth, within which the two influences counterbalance each other in an appropriate way. At the same time the point is reached where something higher - the soul - is integrated as an inner entity within the quadripartite human being.

In its form, in its activities, movements and so forth, the physical body is the expression and the effect of what takes place in the other parts, in the ether body, the astral body, and the "I." In the descriptions from the "Akasha Chronicle" which we have given up to this point, it has become apparent how, in the course of development, these other parts of the human entity gradually intervened in the formation of the physical body. During the Saturn development none of these other parts was as yet associated with the physical human body. But the first beginning of its development was made in that time. However, one must not think that the forces which later acted on the physical body from the ether body, the astral body, and the "I" did not already act on it during the Saturn period. They were already acting at that time, but in a certain sense from the outside, not from within.

The other parts had not yet been formed, had not yet been united with the physical human body as individual entities; but the forces which were later united in them acted as it were from the environment - the atmosphere - of Saturn and formed the first beginning of this body. This beginning was then transformed on the Sun because a part of those forces now formed the separate human ether body, and now acted on the physical body no longer merely from the outside, but from the inside. The same thing occurred on the Moon with respect to the astral body. On the earth the physical body was transformed for the fourth time by becoming the dwelling place of the "I," which now works within it. One can see that, to the eye of the scientist of the spirit, the physical body is not something fixed, something permanent in its form and manner of acting. It is undergoing a constant process of transformation. And such a transformation is also taking place in the current earth period of the body's development. One can only understand human life if one is in a position to form a conception of this transformation.

A consideration of the human organs from the point of view of the science of the spirit shows that these are at very different stages of development. There are organs in the human body which, in their present form, are in a descending, others which are in an ascending development. In future, the former will lose their importance for man more and more. The time of the flowering of their functions is behind them; they will become atrophied and finally disappear from the human body. Other organs are in an ascending development; they contain much which now is only present in a germinal state, as it were: in future they will develop into more perfect forms with a higher function. Among the former organs belong, for instance, those which serve for reproduction, for the bringing into existence of like beings. In future their function will pass to other organs and they themselves will sink into insignificance. There will come a time when they will be present on the human body in an atrophied condition, and one will then have to regard them only as evidences of the preceding development of man.
Other organs, as for instance the heart and neighboring formations, are at the beginning of their development in a certain respect. What now lies in them in a germinal state will reach its full flower only in the future. For in the conception of the science of the spirit, the heart and its relation to the socalled circulation of the blood are seen as something quite different from what contemporary physiology, which in this respect is completely dependent on mechanistic-materialistic concepts, sees in them. In so doing, this science of the spirit succeeds in casting light on facts which are well-known to contemporary science, but for which with the means at its disposal, the latter cannot give anything like a satisfactory explanation. Anatomy shows that in their structure the muscles of the human body are of two kinds. There are those whose smallest parts are smooth bands, and those whose smallest parts show a regular transverse striation.

Now the smooth muscles in general are those which in their movements are independent of human volition. For instance, the smooth muscles of the intestine push the food pulp along in regular movements, upon which the human volition has no influence. Those muscles which are found in the iris of the eye are also smooth. These muscles bring about the movements through which the pupil of the eye is enlarged when the latter is exposed to a small amount of light, and contracted when much light flows into the eye. These movements too are independent of human volition. On the other hand, those muscles are striated which mediate movements under the influence of human volition, for example, the muscles by which the arms and legs are moved. The heart, which after all is also a muscle, constitutes an exception to this general condition. In the present period of human development, the heart is not subject to volition in its movements, yet it is a "transversely striated" muscle. The science of the spirit indicates the reason for this.The heart will not always remain as it is now. In the future it will have a quite different form and a changed function. It is on the way to becoming a voluntary muscle. In the future it will execute movements which will be the effects of the inner soul impulses of man. It already shows what significance it will have in the future, when the movements of the heart will be as much an expression of the human will as the lifting of the hand or the advancing of the foot are today.

This conception of the heart is connected with a comprehensive insight of the science of the spirit into the relation of the heart to the so-called circulation of the blood. The mechanical-materialistic doctrine of life sees in the heart a kind of pumping mechanism which drives the blood through the body in a regular manner. Here the heart is the cause of the movement of the blood. The insight of the science of the spirit shows something quite different. For this insight, the pulsing of the blood, its whole inner mobility, are the expression and the effect of the processes of the soul. The soul is the cause of the behavior of the blood. Turning pale through feelings of fear, blushing under the influence of sensations of shame, are coarse effects of processes of the soul in the blood. But everything which takes place in the blood is only the expression of what takes place in the life of the soul. However, the connection between the pulsation of the blood and the impulses of the soul is a deeply mysterious one. The movements of the heart are not the cause, but the consequence of the pulsation of the blood. In the future, through voluntary movements, the heart will carry what takes place in the human soul into the external world.

Other organs which are in a similarly ascending development are the organs of respiration in their function as instruments of speech. At present by their means man can transform his thoughts into air waves. He thereby impresses upon the external world what he experiences within himself. He transforms his inner experiences into air waves. This wave motion of the air is a rendering of what takes place within him. In the future he will in this way give external form to more and more of his inner being. The final result in this direction will be that through his speech organs which have arrived at the height of their perfection, he will produce his own kind. Thus the speech organs at present contain within themselves the future organs of reproduction in a germinal state. The fact that mutation (change of voice) occurs in the male individual at the time of puberty is a consequence of the mysterious connection between the instruments of speech and reproduction.

The entire human physical body can be considered in this way from the point of view of the science of the Spirit. It was only intended to give a few examples here. In the science of the spirit, both an anatomy and a physiology exist. The anatomy and physiology of the present will have to let themselves be fertilized by the anatomy and physiology of the science of the spirit in a not very distant future, and will even transform themselves completely into the latter. In this area it becomes especially apparent that results such as those given above must not be built on mere inferences, on speculations such as conclusions by analogy, but must only proceed from the true research of the science of the spirit. This must necessarily be emphasized, for it happens only too easily that once they have gained some insights, zealous adherents of the science of the spirit continue to spin their ideas in empty air.

It is no miracle when only phantasms are produced in this way, and, in fact, they do abound in these areas of research. One could, for instance, proceed to draw the following conclusion from the description given above: Because the human organs of reproduction in their present form will in the future be the first to lose their importance, they therefore were the first to receive it in the past, hence they are in a sense the oldest organs of the human body. Just the contrast of this is true. They were the last to receive their present form and will be the first to lose it again.

The following presents itself to spiritual scientific research. On the Sun, the physical human body had in a certain respect moved up to the level of plant existence. At that time it was permeated only by an ether body. On the Moon it took on the character of the animal body, because it was permeated by the astral body. But not all organs participated in this transformation into the animal character. A number of parts remained on the plant level. On the earth, after the integration of the "I," when the human body elevated itself to its present form, a number of parts still bore a decided plant character. But one must not imagine that these organs looked exactly like our present-day plants. The organs of reproduction belong among these organs. They still exhibited a plant character at the beginning of the earth development. This was known to the wisdom of the old Mysteries. The older art which has retained so much of the traditions of the Mysteries, represents hermaphrodites with plant-leaf like organs of reproduction. These are precursors of man which still had the old kind of reproductive organs (which were doublesexed). For example, this can be seen clearly in a hermaphrodite figure in the Capitoline Collection in Rome. When one looks into these matters one will also understand for instance the true reason for the presence of the fig leaf on Eve.

One will accept true explanations for many old representations, while contemporary interpretations are, after all, only the result of a thinking which is not carried to its conclusion. We shall only remark in passing that the hermaphrodite figure mentioned above shows still other plant appendages. When it was made, the tradition still existed that in a very remote past certain human organs changed from a plant to an animal character.

All these changes of the human body are only the expression of the forces of transformation which lie in the ether body, the astral body, and the "I." The transformations of the physical human body accompany the acts of the higher parts of man. One can therefore understand the structure and the activity of this human body only if one absorbs oneself in the "Akasha Chronicle," which shows how the higher changes of the more spiritual and mental parts of man take place. Everything physical and material finds its explanation through the spiritual. Light is shed even on the future of the physical if one studies the spiritual.