In GA 351 Steiner names the liver the sun organ: it cooks the sun's fire into bile, while the lung, its polar opposite, serves the moon.
The Liver as Sun Organ in Anthroposophy is Rudolf Steiner's teaching that the liver is the bodily organ through which the sun's fire works in the human being, cooking that fire into bile and radiating it through the blood as warmth, will, and temperament. Steiner developed the idea on 13 October 1923 in Dornach, in the workmen's lecture published in Man and World: How Spirit Works in Nature (GA 351), answering a question about photographed snowflakes. The liver stands in polarity to the lung, the moon organ that secretes crystal-forming mucus: peoples of the hot zones carry relatively large livers and smaller lungs, peoples of the ice the reverse. A person with a generous liver has fire; a shrunken liver leaves the person phlegmatic. Modern chronobiology echoes the picture: the liver keeps its own daily clock, entrained to the cycle of daylight and feeding.
Steiner's picture of the liver as sun organ begins with a workman's question about snowflake photographs. Snow and ice crystals reveal where the sun's power is weak; the liver reveals where it is strong. In the liver the sun's fire is cooked into bile, and bile, spreading through the blood, gives a person inner fire, drive, and even wrath when it flows too freely.
In Steiner's Own Words
The big difference between people in hot regions and Eskimos, people in cold regions, lies in the difference in the formation of their livers and lungs. Eskimos have relatively large lungs and small livers in relation to their bodies, and people in hot zones have relatively smaller lungs and large livers. So you see, people in regions where ice flowers and ice crystals form differ from others in that they have relatively small livers and large lungs in relation to their bodies. And people in regions where nature does not tend to form such figures, but where the sun always melts everything away, have the peculiarity of having relatively small lungs and large livers. Whenever we ask about something in nature, including ice flowers, we must always look at humans. If we do not start from humans, we understand nothing in nature, absolutely nothing.
What it Means Today
Steiner's claim that solar activity promotes liver activity reads differently since chronobiology found the liver keeping time on its own. In 2000, Francesca Damiola and colleagues in Ueli Schibler's laboratory at the University of Geneva showed in the journal Genes & Development that the mouse liver carries its own circadian clock, one that can be uncoupled from the master clock in the brain simply by changing when the animal eats. The liver cell does not merely take orders from the light-sensing brain: it keeps a daily rhythm of its own, set by feeding and the alternation of day and night. Later work has counted hundreds of liver genes, governing bile acids, blood sugar, and detoxification, that rise and fall on this roughly 24-hour cycle. None of this proves Steiner's cosmology; it does show that his instinct, that the liver is the organ most intimately bound to the sun's rhythm, points at something physiology now measures.
Thalira synthesis: the liver is the hearth of the human house, where outer sunlight, taken in as food, is cooked a second time into the inner fire Steiner called bile, which is why a cooling of the will is so often the first sign of a cold hearth. The lecture carries a practical corollary: Steiner recommends warmth and light on the abdomen for the shrunken liver, and regular mealtimes are, on the Geneva evidence, the surest way to keep its clock in phase with the sun's day.
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