Following the theme of warmth in the lectures at the 2025 Natural Science Section conference at the Goetheanum.
The Earth’s Warmth Sheath
In his fairy tale “The Little Matchstick Girl,” Hans Christian Andersen describes a poor young girl who tries unsuccessfully to sell matches on a freezing New Year’s Eve. One by one, she burns her matches, and her desire for different kinds of warmth is illuminated: she longs for physical, social, emotional, and spiritual warmth. The different aspects of warmth are made clear in the fairy tale through their absence.
Physicist Matthias Rang told this story at the beginning of his lecture on the Earth’s thermal envelope—its “warmth sheath.” We are largely unaware of warmth, usually only taking notice when it is missing or when it turns into heat. Warmth penetrates space but is itself insubstantial. Physically, warmth is an internal movement of substances, a deeper characteristic than outer movement. Warmth is inwardness and mobility, but not substance; it is a transition to the etheric. The effect of warmth, whereby substances are transformed into a more volatile state, also shows warmth’s proximity to the etheric.
In the lecture, the Earth’s warmth sheath was illustrated and explored using an experiment with the flight of a hot air balloon that had been conducted earlier. Differences in temperature are a defining characteristic of the air. For this experiment, the thermal sheath was investigated by measuring the amount of thermal radiation coming from above and from below. The data clearly showed “windows” in the atmosphere through which heat radiation freely passes and moisture-saturated “mirrors” that reflect the heat radiation upwards or downwards. Normally, the Earth’s atmosphere has a well-balanced heat budget with radiation in equilibrium. But in our times, the Earth is becoming increasingly closed off, and the “windows” through which heat flows are getting smaller. This is like a mirror of our unconnected and unconscious deeds.
Ectothermic Animals and the Wonder of Bees
The balancing of the warmth sheath exhibited by the Earth is not a given in living organisms, as demonstrated by ectothermic (“cold blooded”) animals. Biologist Johannes Wirz explained how ectothermic insects are entirely devoted to and dependent upon their surroundings during their life. They have a wide variety of forms that correspond to the diverse environmental niches within which they live. By contrast, vertebrates have internalized the environment during their evolution, culminating in the internal production of warmth in mammals and birds. Within the world of insects, however, there are special exceptions among colony-forming species such as the honeybee. Honeybees can regulate the temperature within their hive to maintain an internal temperature of approximately 37°C [98.6°F] in summer through cooling and around 17 °C [~63°F] in winter through warming. This is only possible for the bees to do as a community. As a community, the bee colony also has a high degree of inner agentic development, as we see in their symbolic language of waggle dances. Steiner indicated that the agency of bee colonies evolved to a degree like an initiate during meditation. We humans could learn a lot for the future of the Earth from their devoted collaboration.
Internalizing Warmth
And what about heat in vertebrates? Lizards basking on a rock seem a bit sluggish, but physiologically, there is a lot going on: they’re heating themselves by several degrees, their entire metabolism is changing, and they’re regaining mobility. Their physiology and locomotion depend on this heat bath. Mammals and birds have internalized the heat. Polar bears and penguins are extremely good at dealing with internal warmth and can withstand temperatures as low as -60°C [-76°F]. In birds and mammals the heat comes from inside—they are endothermic—and it is regulated within species-specific limits.
The body’s heat production doesn’t have its own organ. Heat production in endotherms is connected to nearly all the organs and structures of an organism. Metabolism and musculature are the sources of heat production. To maintain it, an endothermic mammal must eat about ten times more than an ectothermic animal of the same weight. During mammalian evolution the entire body was reorganized in connection with the evolution of endothermy, as described by the paleontologist Susanna Kümmell. The structures that regulate heat, such as the nasal conchae (spongy bones of the nasal passages) and the diaphragm, evolved between the end of the Paleozoic era and the middle of the Mesozoic era, a period of approximately 100 million years. During this time span, mammals further evolved sustainable locomotion and enhanced sensory abilities, particularly in hearing. These provided a basis for stronger engagement with the world and enhanced evolution of inner processing of impressions. The animals’ inner soul activity was able to emerge further. Parental care increased and milk evolved, enabling a stronger bond of the offspring with the mother. Milk is a very special fluid! It not only nourishes but also provides hormones and antibodies to the offspring that will support its future life. Milk delivers physical and soul warmth.
Warmth provides a physiological sheath through which the soul can become more present in the body, during the evolution of mammals. And it shows its great transformative power in the connection of the evolution of endothermy and the reorganization of all the mammalian organ systems.
Endothermy: a Basis for Increased Autonomy
Evolutionary biologist Bernd Rosslenbroich continued the discussion by delving deeper into the physiology of ectothermic and endothermic animals. He showed that a specific form of cellular calcium metabolism, which is lacking in ectothermic animals, enables the formation of self-generated heat in muscles without the need to trigger external movement. This is one factor among many that contribute to the ability to generate body heat. The evolution of endothermy is a complex, systemic process involving a multitude of factors. The process leads to increasing independence of endothermic animals from external thermal conditions. It is a very important step in a complex series of steps in the evolution of mammals towards greater autonomy, from the simplest organisms to humans and other modern mammals. Endothermy and the organ processes related to it allow individuals to become more independent of their environments and enable more flexibility in behavior and movement. For example, mammals engage in play—and not only the young. In humans, endothermy forms a basis for even higher degrees of autonomy, such as mental perception and the ability for self-determination and free action.
I Live in My Warmth
With a closer look at the body heat of endotherms as mammals or human beings it becomes obvious that the body heat is not entirely constant, neither locally nor temporally, but rather exhibits a local and temporal structured organization. In his lecture on the thermal organization of human beings, physician Reiner Penter referred to the fairly constant temperature of our core (internal organs) and the temperature of our peripheral parts (limbs and skin), which is influenced by the external temperature. At rest, 70 percent of a person’s body heat is generated in the internal organs, especially in the heart, and only a small amount in the muscles. When in motion, however, up to 90 percent of the heat comes from the muscles of the limbs. The head gives off especially large amounts of heat. Core and periphery temperatures are subject to the circadian heat rhythm but in opposite directions: at night, the core temperature drops and the temperature in our peripheral members rises. During the day, the core temperature rises, and the temperature in our limbs and skin falls. Throughout the day, the soul follows the heat rhythm of the core: concentrated in the morning when the core temperature is lower and expansive at the end of the day when the core temperature is higher. I live within my warmth. The warmth ether is oriented toward the life of the soul. Under extreme temperatures, however, it is difficult to remain present in our souls.
Illness often involves an imbalance or extreme of warmth, for example, in the case of fever. The fever temperature curve performs either a clearly structured pattern or a less organized warmth distribution. The structured pattern of warmth is conducive to healing. A well-structured fever can contribute to healing other illnesses as well. So we see again how important the temporal structure of warmth is for physiological processes and for the well-being of the soul and spirit.
The Transformation of Warmth in Agriculture
The transformative power of warmth was clearly demonstrated in the contribution by farmer and lecturer Martin von Mackensen. Sustainable agriculture has learned how to actively manage the heat processes in soil. As a metaphor for this, Joseph Beuys’ art project of 7,000 oak trees and basalt columns in Kassel, Germany, was presented, which Martin von Mackensen participated in as a 15-year-old. The highlight of the process was the remelting of a gold crown into a hare and a sun, to which Beuys added an inscription: “Everything depends on the warmth of thought. That is the new quality of will.” This exhibit is symbolic of the farmer’s work upon the Earth. Harnessing the warmth processes in agriculture opens a wide field of possibility. Compost made from cow manure and organic residues, mixed with specific preparations, generates heat that must be monitored by the farmer as “compost master.” The compost must not become too warm nor too cool, and it also needs to breathe. Steiner even described compost as an organ. Compost fertilization brings warmth to the soil. With the help of manure, the growing plant organism organizes itself—a living transformation of living warmth. The field and garden plants of the agricultural organism produce more than just food; they also produce roots. The roots absorb substances for the plant, and thus connect with the soil and transform it. This is like a germinating force for the macrocosm.
The Evolution of the Earth’s Warmth Sheath and Humankind
The macrocosm, the Earth, the evolution of its thermal sheath, and the role of human beings was the focus of microbiologist and marine researcher Meinhard Simon’s talk. The Earth’s abundant water and greenhouse gases play a major role in the heat balance of the earth. The natural greenhouse effect provides us with a livable environment; without it, we would have an average temperature of -18°C [-0.4°F]. Small changes in the amount of greenhouse gases have a fundamental impact on the Earth’s warmth sheath, as we see today with anthropogenic climate change. Thermal conditions are different on other planets. Venus has a very hot surface of several hundred degrees, while Mars is very cold.
Meinhard Simon explained how the Earth cooled relatively rapidly from the hot state of its early days, when water vapor fell from the atmosphere onto the Earth’s surface in a long period of continuous rains that created the oceans. A large amount of CO₂ was also absorbed from the atmosphere by organisms that were microbes for long periods of time before they became multicellular organisms, and was then stored within the Earth as their organic remains (kerogen, coal, crude oil, and limestone). This significantly reduced the CO₂ content of the atmosphere. The oxygen in the atmosphere was entirely created by photosynthesizing microbes and plants. Both processes show how the composition of the atmosphere is intimately connected with life. Between 700 and 400 million years ago, the oxygen produced by living organisms formed the ozone layer, which shields the Earth from UV radiation and made the continents habitable.
Throughout Earth’s long history, there have been major fluctuations in the CO₂ content of the atmosphere and in the Earth’s heat balance (ice free ages or “hothouses” and ice ages or “icehouses”.) From the Cenozoic (Tertiary) era onwards, the temperature fell continuously until the last icehouse, the time of ice ages. According to geological rhythms, we are currently experiencing an interglacial period. Before the ice ages, seven million years ago, the first known representative of human ancestors (Hominini) appeared in the form of Sahelanthropus, when the average temperature of the Earth had fallen below 20°C [68°F]. The genus Homo followed two million years ago, with the average Earth temperature of 14.5°C [58°F]. These lower temperatures on the planet were certainly important for the development of human consciousness.
The Earth has the ability to maintain a stable temperature. Unlike its neighboring planets, it manages to remain within a temperature range that is favorable for life across large parts of its surface. The early days of the Earth were like an embryonic phase, during which microorganisms helped shape the Earth’s outer sphere, our atmosphere, until conditions became suitable for other life forms. Steiner spoke about how spiritual human beings work together with the spiritual hierarchies on Earth. In connection with this spiritual scientific description, Meinhard Simon considered the extent to which microorganisms can be regarded as organs of the higher hierarchies and of the suprasensible human ancestors in their work, and how in this way the suprasensible human ancestors helped shape the environment into which they later incarnated.
Since prehistoric times, human beings have opened up regions of the Earth through culture, and the resulting microclimates created by clothing and buildings, etc. What will it mean for the evolution of human beings when we reach significantly higher global temperatures again due to human-made global warming? Humans, with their actions of global proportions, have become responsible for the Earth’s climate and the well-being of our shared environment.
Translation Joshua Kelberman
Image Artistic work at the conference. Photo: Nicolas Prestifilippo
