Recently on facebook one of the topic on my wall was about blood, and there was way too much to say about it, for the answer to fit in a simple post, it is a profound subject that needs an article, not an elusive and quick answer.
Some think that this subject is part of legends and myths and that we should stop watching tv shows and films, that blood is an analogy for other matters (mineral one especially). I won't deny the fact that blood is often used as an anlogy, but also as the principal subject, minera, patient of the Alchemical Magnum Opus.
As all matter, (whatever could say the only-mineral-alchemy persons, thinking that only sulfur, mercury and salt exists exclusively in metallic subjects), it can evolve in favorable conditions.
Sigismund Bacstrom tells us in his "Rosicrucian Aphorisms and Process" that it is "the Operis maximi Antiquorum Sapientium" or hear, the greatest operation of the antique wisdom. Without ambages he is informing us about the principal subject : the blood of a young man.
Seal of the Rosicrucian Society, from the admission copy of the Dr.Bacstrom.
You see clearly the "source" of the matter.
I won't give all the details of the text, stressing only on the protocol (seemingly at first sight perfectly clear and complete, but it is in reality incomplete) which is given. Actually, it is not the most interesting that is hiden, but only a very common key (for that perdio of time). He was quite charitable with us. A lot of other books and resources speak about the work on blood. A complete artist had to work at that time on all kingdoms. I also read some processes about volatile salts of human skulls... There was no limits to their visions and experiences.
The occult role of blood in huge. Obviously we hear about it stories of vampires, where it is considered as fluid of life, in shamanism, in psychogenealogy where it is playing the role of memory bank of the ancestors, in magick, where it is a vital charge/force/energy for the realisation of an objective - some will even qualify this, as "red magick", even though often, it is dipped in "black", a drop of blood can rise the capacity of charge of a tincture in an incredible way, exactly as gold. We also can see blood as a personnal "signature", as would do a drop of saliva, sweat, etc. It is thus, a kind of "gold".
So, we saw that it is a fluid of life force, memoiry, capacitor of force and a signature. We can understand now that the Stone made out fo blood is a maximization of the vital fluid in in. Rising, exalating the quality of blood, having cooked it and perfected, cleaned, we then can ingest it and we are transmuted.
This is why you have to take your blood, and not as indicated in Bacstrom's text, the one of a young men ... Not because of the vitale force, pretext to take the one of a healthy young men, but more because of the fact that your personnal, familial, and human karma is present in it.
Cooking his own blood into a Stone, it is perfecting yourself, evolving in a quicker way.
But you have to know that the process is very hard psychically to undertake, alike any animal ways, and you have to be a good magus/mystic to avoid all the pitfalls of such work. It is said that you need a Mineral Stone befaore, or even an Astral Stone (dew, rain, snow etc).
We see in vampires film, alike the new "Dracula Untold" (2014), that blood confers the initiation of that state. What happens ? TheVampire will give to drinnk his own blood to one of his "kid", this one is temporarily "transmuted" (retrograded would I say - involutive transmutation). He has then the symptoms of the vampire. If ever he drinks human blood, his destiny is sealed, he remains a vampire.
We have the same thing in the Christian religion. Christ's blood is transmutative. Analogically of the Powder of Transmutation, but here in the human and spiritual area.
Jean Dubuis in one of his documents on the Graal tells us this :
"In the initiatory path, that is to say, in the rising levels of consciousness, changes occur in both the psyche and the physic of the adept. In particular, blood properties change. It says in the Bible that "the Spirit is in the blood." The word Spirit is not to be confused with the word soul. In ancient chemical and alchemical texts, the passage in the distillation of spirits is the passage of the Philosophical Mercury. This Spirit endows the blood of a high regenerative power that opens the centers corresponding to high levels. This blood acquires alchemical powers proportionated to the level reached by the adept.
In the case of the adept at Tiphereth, blood acquires the properties of seed of gold. The dried blood powder transmutes copper, mercury, silver into gold; However, tin, iron and lead are not accessible to him. This powder rises all beings who consume it,and that are already on the path, at Tiphereth."
Farther we read :
"The symbolism in the Communion of the catholic Church is an occultation of the possibility of redeeming of men through the transmuted blood.
A depth study of this question leads us to the following conclusions : the dried powder of blood of an adept can realize a transmutation, even in the hands of a novice person, only very few basic knowledges are enough. But, we believe that the awakening of the adept can only be done via his own blood."
This is very interesting. The blood of a adept is so transformed that it's own nature even change. It is possible that it is no more "iron" in the hematias, but possibly a "gold". It is then, down to the center of production of blood in the red marrow and spleen that the transmutation operates and is the most present.
Alchimists also do this with the Cosmic Blood, or Spiritus Mundi. But it is here another subject. Which comes normaly after the Stone of Blood. (Alike the steps of a stair, if we want to go from an extreme to another, we need mediums between the two).
Yogis too transmute their bodies by a kind of internal alchemy. The Christic Force is said residing in Ajna, and going down into the most subtles bodies at first, then, condensing itself physically as a warm nectar with a subtle taste. Some call it Rasa, some Soma. Depending of their definition. It is when the whole body is charged, impregnated of this fluid that the yogi becomes a "christ yogi" as state the definition of the Kriya yogis (Paramahamsa Yogananda for example). Do not mistake "Christ" with "Jésus". Jésus became Christ, yes, but any kind of human can be Christ, because this spiritual state is universal, and not localied in only one kind of matter/men. It is fore, and foremost, an energy.