Oxalic acid is Steiner's acid of life: present wherever an etheric body works, renewed by it, and turned into formic acid by the astral body.
Oxalic Acid in Anthroposophy is the substance Steiner identifies with life as such, the etheric pole of a pair whose upper member is formic acid. In the ninth of his bee lectures to the Goetheanum workmen at Dornach on 22 December 1923, printed in Nine Lectures on Bees (GA 351), he states the rule plainly: wherever there is life there is oxalic acid and an etheric body, and the etheric body is what keeps renewing it. Plants carry it everywhere, most densely in wood sorrel and clover; the human lower body, liver, spleen, kidneys and intestines, carries it too. It becomes usable only when an astral body raises it into formic acid, the acid Steiner ties to sensation, intelligence and the soul. Formic acid distilled in a retort from oxalic acid and glycerine looks identical and is, in his phrase, dead. Anthroposophic pharmacy still prescribes Oxalis preparations on exactly that reading.
Oxalic acid is the acid Steiner places at the bottom of the life-process, where the etheric body works before any soul has touched it. He treats it less as a chemical curiosity than as a boundary: below it, mere life; above it, once an astral body has done its work, formic acid and the beginnings of sensation. Wood sorrel and clover are where the plant world shows it most openly.
In Steiner's Own Words
One only fully understands these things when one asks: How is it then with the oxalic acid? Oxalic acid is essential for all that has life. Wherever there is life, there is oxalic acid, an etheric body. The etheric body brings it about that the oxalic acid is renewed. But the oxalic acid never becomes a formic acid that can be used by the human or animal organism unless it is first transformed by an astral body from oxalic into formic acid. The formic acid which I here extracted from the oxalic acid, is of no use at all to the human or animal organism. It is an illusion to think it can be of use; it is dead.
What it Means Today
The clinical thread runs unbroken. Steiner gave these lectures two years after he and Ita Wegman opened the clinical-therapeutic institute at Arlesheim in 1921, and the pharmaceutical laboratory that grew alongside that work later took the name Weleda. The indication he gives in this very lecture is precise and still recognisable in practice: a patient short of formic acid whose trouble sits in the lungs may be given formic acid, but a patient whose trouble sits in the liver or the intestines must be given oxalic acid instead, drawn from wood sorrel or from the clover of the fields, and left to make the conversion himself. Anthroposophic pharmacies work from that instruction rather than around it. Weleda's Oxalis (wood sorrel) ointment is still dispensed as a warmed abdominal compress for cramping pain, prescribed for the abdominal region Steiner names and not for the chest.
Thalira synthesis: the strangest confirmation came from microbiology, not from anthroposophy. In 1985 Milton Allison and his colleagues described an anaerobe living in the human colon that feeds on oxalate and splits it into formate and carbon dioxide, and they named it Oxalobacter formigenes, the oxalate-eater that makes formate. Steiner's retort had produced formic acid and carbonic acid from oxalic acid and glycerine, and his lecture insisted that small creatures perform this same transformation out in nature and inside us. Sixty-two years later a creature small enough to have been missed entirely was found doing it in the gut, and its Latin name says what it does.
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