Can someone point to where RS talks of ‘Spiritual Substance’ please?
He talks of ‘Cosmic Substance’ often in the course, but Spiritual Substance I can not recall ever hearing of this.
…………………… “The physical body is built up within the physical world as a completely separate being, and the same is true of the spiritual body in the spiritual world. The human being likewise has an inside and an outside in the physical world, and the same is true in the spiritual world. And just as we take in substances from our physical surroundings and incorporate them into our bodies, we also take in spiritual substance from our spiritual surroundings and make it our own. This spiritual substance is eternal nourishment for human beings. We are born out of the physical world, and yet we are independent beings separate from the rest of the physical world. In the same way, we are born out of the spirit through the eternal laws of the good and the true, and yet we are separate from the spiritual world outside us. We will call this independent spiritual entity the “spirit body.”” – Theosophy
Perhaps this appendix to the Agriculture Course is what you’re after: https://books.google.com/books?id=VAy11h30A5sC&pg=PT216…
It is in contrast to “earthly substance” in the introduction
“We have tried, again from a particular aspect, to place the human being into the universe. Today we wish to put the subject forward in a way which will, as it were, weld everything into a whole. During our physical life we live upon the earth; we are surrounded by those events and facts which are there because of the physical matter of the earth. This matter is moulded and shaped in the most varied manner so as to be adapted to the beings of the kingdoms of nature, up to the human form itself. The essential element in all this is the physical matter of the earth. Today — because we shall immediately have to speak about its opposite — let us call this matter the physical substance of the earth, comprising all that provides the material basis for the various earthly forms; and then let us differentiate from it everything in the universe which is the opposite of this physical substance, namely spiritual substance. This last is the basis not only of our own soul, but also of all those formations in the universe which, as spiritual formations, are connected with physical formations.
It is not right to speak only of physical matter or physical substance. Think only of the fact that we must place into the total picture of the world the beings of the higher hierarchies. These beings of the higher hierarchies have no earthly substance, no physical substance, in what in their case we would call their bodily nature. What they have is spiritual substance. When we look upon what is earthly, we become aware of physical substance; when we can look upon what is outside the earthly, we become aware of spiritual substance.
Today people know little of spiritual substance. That is why they also speak of that earth-being, who belongs both to the physical and the spiritual — the human being — as though he, too, only possessed physical substance. This, however, is not the case. Man bears both spiritual and physical substance in himself in so remarkable a way as to astonish anyone who is not accustomed to pay heed to such matters. If, for example, we consider that element in man which leads him into movement, namely what is connected with the human limb-system and its continuation inwards as digestive activity, then it is incorrect to speak primarily of physical substance. You will soon understand this still more exactly. We only speak correctly about the human being when we regard the so-called lower part of his nature as having as its basis what is in fact spiritual substance. So that, if we were to represent the human being schematically, we would have to say: The lower man actually shows us a formation in spiritual substance, and the more nearly we approach the human head, the more is man formed of physical substance. Basically the head is formed out of physical substance; but of the legs — grotesque though this may sound — it must be said that essentially they are formed of spiritual substance. So that, when we approach the head, we must represent the human being in such a way that we allow spiritual substance to pass over into physical substance; in the human head where in particular physical substance is contained. Spiritual substance, on the other hand, is diffused in a particularly beautiful way just where — if I may put it so — man stretches out his legs, stretches out his arms, into space. It is really as though the most important matter for arm and leg is precisely this being filled with spiritual substance, as if this is their essence. In the case of arm and leg it is really as though the physical substance were only swimming in the spiritual substance, whereas the head presents a compact formation composed of physical substance. In a form such as man possesses, however, we must differentiate not only the substance, but also the forces. And here again we must distinguish between spiritual forces and earthly, physical forces.
In the case of the forces, things are completely reversed. Whereas for the limb-system and digestion the substance is spiritual, the forces in the limbs, for instance in the legs, are heavy, physical forces. And whereas the substance of the head is physical, the forces active within it are spiritual. Spiritual forces play through the head; physical forces play through the spiritual substance of the limb and metabolic system in man. The human being can only be fully understood when we distinguish in him the upper region, his head and also the upper part of the breast, which are actually physical substance worked through by spiritual forces (I must mention that the lowest spiritual forces are active in the breathing). And we must regard the lower part of man as a formation composed of spiritual substance, within which physical forces are working. Only we must be clear as to how these things are interrelated in man, for the human being also projects his head-nature into his whole organism, so that the head — which is what it is because it is composed of physical substance worked through by spiritual forces — the head also projects its entire nature into the lower part of the human being; and what man is because of his spiritual substance, in which physical forces are at work, this, on the other hand, plays upwards into the upper part of the organism. In these activities in the human being there is mutual interaction. Man can in fact only be understood when he is regarded in this way, as composed of physical-spiritual substantiality and physical-spiritual dynamics, that is to say what is of the nature of forces.
This is something of great significance. For if we look away from external phenomena, and enter into the inner being, it becomes clear to us, for instance, that no irregularities can be allowed to enter into this apportioning of what is of the nature of substance and of forces in the human being.
If, for example, what should be pure substance, pure spiritual substance in man, is too strongly penetrated by physical matter, by physical substance — if, that is to say, physical substance which should in fact tend upwards towards the head makes itself too strongly felt in the metabolism — then digestion becomes too strongly affected by the head-system, and man becomes ill; certain quite definite types of illness then arise. And then the task of healing consists in paralyzing, in driving out, the physical substance-formation which is intruding into the spiritual substantiality. On the other hand, when man’s digestive system, in its peculiar manner of being worked through by physical forces in spiritual substance, when this digestive system is sent up towards the head, then the head becomes, as it were, too strongly spiritualised, then there sets in a too strong spiritualisation of the head. And now, because this also presents a condition of illness, care must be taken to send enough physical forces of nourishment to the head, so that they reach the head in such a way that they do not become spiritualized.
Anyone who turns his attention to man in health and sickness will very soon be able to perceive the usefulness of this differentiation, if he is really concerned with truth, and not with external illusion. But something essentially different also plays into this matter. What here plays in — the fact that man feels himself as a being constituted in the way I have described — this at first remains for the ordinary consciousness of today below in the unconscious. There, certainly, it is already present; and there it emerges as a kind of mood, a kind of life-mood of man. But it is spiritual vision alone that brings it to full consciousness, and I can only describe this spiritual vision to you thus: The man who knows from present-day initiation-science this secret of the human being, namely that the head is the most important, the most essential organ which needs physical substance with spiritual forces; who knows further that the most essential thing in the system of limbs and metabolism is spiritual substance which needs physical forces — the forces of gravity, of balance, and the other physical forces in order to exist; who can thus penetrate with spiritual vision into this secret of the human being and who then turns his gaze back to this human, earthly existence — this man must acknowledge himself as a tremendous debtor to the world. For he must admit that in order to maintain his human existence he requires certain conditions; but through these very conditions he becomes a debtor to the earth. He is continually withdrawing something from the earth. And he finds himself obliged to say that the spiritual substance, which as man he bears within himself during earthly existence, is actually needed by the earth. When man passes through death, he should in fact leave this spiritual substance behind him for the earth, for the earth continually needs spiritual substance for its renewal. But this man cannot do, for he would then be unable to traverse his human path through the period after death. He must take this spiritual substance with him for the life between death and a new birth; he needs it, for he would disappear, so to speak, after death, if he did not take this spiritual substance with him.”