In the astral body the animal form arises, outwardly the form as a whole, inwardly the formation of the organs. The sentient animal substance is, then, an outcome of the form-giving activity of this astral body. Where this process of formation is carried to its conclusion, the animal is produced.
In man it is not carried to its conclusion. At a certain point on its way it is held up, blocked.
In the plant we have material substance transformed by the forces raying inward to the earth. This is the living substance. It is continually interacting with the lifeless [matter]. We must conceive that in the plant, living substance is perpetually being separated out of the lifeless. It is in the living substance that the plant form then appears as a product of the forces raying in towards the earth. Thus we have one stream of substance. Lifeless substance transforms itself into living; living transforms itself into lifeless. In this stream the plant-like organs come into being.
In the animal the sentient substance comes forth from the living, as in the plant the living from the lifeless. Thus there is a twofold stream of substance. The life is not carried to the point of formed living in the etheric. It is kept in flow, and form inserts itself through the astral organization into the streaming life.
In man, this latter process too is kept in flow. The sentient substance is drawn into the realm of a still further organization. This we may call the ego-organization. The sentient substance transforms itself once more. A threefold stream of substance is produced. In this, man's inner and outer form arises. Through this it becomes the bearer of self-conscious spiritual life. Down to the smallest particle of his substance, man in his form is a result of this ego-organization.
We can now trace these processes of formation in their material aspect. The transformation of substance from the one level to the next appears as a separation of the upper level from the lower, and a building of the form out of this separated substance. In the plant, out of the lifeless substance the living is separated. In this separated substance, the etheric forces work, raying inward to the earth, creating form. To begin with, there takes place not an actual separation but an entire transformation of physical substance by the etheric forces. This, however, only happens in the formation of the seed. Here the transformation can be complete, because the seed is protected by the surrounding maternal organization from the influences of the physical forces. But when the seed formation is freed from the maternal organization, the working of the forces in the plant divides; in one direction, the forming of substance is such as to strive upward into the realm of the etheric, while in the other it strives back again to physical formation. Parts of the being of the plant arise that are on the way to life and those which are on the way to death. The latter then appear as the excretory members of the plant organism. The bark-formation of the tree is a particularly characteristic example in which we may observe this excretory process.
In the animal there are dual processes of separation, and dual processes of excretion. The plant-process of excretion is not carried to a conclusion but kept in flow, and there is added to it the transformation of living substance into sentient. This sentient substance separates itself from the merely living. We have, therefore, on the one hand, substance that is striving towards sentient existence, and on the other, substance that is striving away from it to the condition of mere life.
In a living organism there is, however, a reciprocal relationship of all parts. Hence in the animal the excretion towards the lifeless realm, which in the plant approaches very nearly to the outer lifeless world, the mineral, still remains far removed from mineral nature. In the bark-forming process of the plant, we see the forming of a substance which is already on the way to mineral nature and loosens itself from the plant-organism increasingly, the more mineral it becomes; this appears in the animal as the excreted products of digestion. These are farther removed from the mineral nature than the excretions of the plant.
In man, that part is separated out of the sentient substance which then becomes the bearer of the self-conscious spirit. But a continual separation is also brought about, for in the process, substance is produced that strives towards the merely sentient faculty. Animal nature is therefore present within the human organism as a perpetual excretion.
In the animal organism, in the waking stage, the separation and formation of what is excreted, as well as the excretion of the sentient substance, stand under the influence of the astral activity. In man there is added the activity of the ego organism. In sleep the astral and the ego-organism are not directly active. But the substance has been taken hold of by their activity and continues in it as though by inertia. A substance once formed through and through as occurs by the workings of the astral and ego-organization, will go on working in the way of these organizations in the sleeping state, as it were, out of inertia.
We cannot therefore speak of any merely vegetative action of the organism in sleeping man. Even in sleep, the astral and ego-organizations work on in the substance that has been formed under their influence. The difference between sleeping and waking is not to be represented as an alternation of human and animal with physical and vegetative modes of action. The reality is altogether different. In waking life the sentient substance, and that which can act as a bearer of the self-conscious spirit, are lifted out of the organism as a whole and placed at the disposal of the astral body and ego-organization. The physical and the etheric organism must then work in such a way that the forces raying outward from the earth and in toward it, alone are active in them. True, they are also taken hold of by the astral body and ego-organization yet only from outside. In sleep, they are taken hold of inwardly by the substances that come into existence under the influence of astral body and ego-organization; while man is sleeping, from the universe as a whole only the forces radiating out of the earth and in toward it work upon him, there are working on him from within, the substance-forces which the astral body and ego-organization have prepared.
If we call the sentient substance the residue of the astral body, and that which has arisen under the ego-organization's influence its residue, then we may say: in the waking human organism the astral body and ego-organization themselves are working, and in the sleeping human organism their substantial residues are at work.
In waking life man lives in activities which bring him into connection with the outer world through his astral body and through his ego-organization; in sleep his physical and etheric organisms live on what has become the material residue of these two organizations. A substance absorbed by man, both in the sleeping and in the waking state, like oxygen in breathing, must therefore be differentiated as to its mode of action in the two conditions. According to these two conditions, the oxygen absorbed from without has the effect not of awakening, but of putting man to sleep. Increased uptake of oxygen leads to abnormal drowsiness. In waking life the astral body battles perpetually against the soporific influence of the absorption of oxygen. When the astral body suspends its work upon the physical, the oxygen unfolds its proper nature and sends the man to sleep.