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The physical state of life

Updated: Mar 4

“Dreams take place in liquid environments.” -Esther Leslie, Liquid Crystals: The Science and Art of a Fluid Form (2016) The idea of life as a kind of compromise between solidness and fluidity is not new. Lao Tzu says this in Tao Te Ching chapter 76: “A man is born gentle and weak. At his death he is hard and stiff. Green plants are tender and filled with sap. At their death they are withered and dry. Therefore the stiff and unbending is the disciple of death. The gentle and yielding is the disciple of life. Thus an army without flexibility never wins a battle. A tree that is unbending is easily broken. The hard and strong will fall. The soft and weak will overcome.” Ovid wrote, in the year 9 AD, in the opening of Metamorphoses: “Unfirm the earth, with water mix'd and air; Opaque the air; unfluid were the waves. Together clash'd the elements confus'd: Cold strove with heat, and moisture drought oppos'd; Light, heavy, hard, and soft, in combat join'd” (Ovid 2006). Haeckel’s The Wonders of Life: A Popular Study of Biological Philosophy (1904) discusses the “chief physical property,” or “peculiar thickness and consistency” of living matter: “The physicist distinguishes three conditions of inorganic matter—solid, fluid, and gaseous. Active living protoplasm cannot strictly be described as either fluid or solid in the physical sense. It presents an intermediate stage between the two which is best described as viscous; it is best compared to a cold jelly or solution of glue. The cause of this softness is the quantity of water contained in the living matter, which generally amounts to half of its volume and weight. The water is distributed between the plasma molecules, or the ultimate particles of living matter, in much the same way as it is in the crystals of salts, but with the important difference that it is very variable in quantity in the plasm. On this depends the capacity for absorption or imbibition in the plasm, and the mobility of its molecules, which is very important for the performance of the vital actions.” Galen of Pergamon (Galen et al. 1997) said, in Works on Human Nature: Volume 1, Mixtures (De Temperamentis) that earth, air, water, and fire are pure representatives of the fundamental qualities hot, cold, wet, and dry, but that in animals these qualities always occur in mixed form. If we call an animal wet, we only mean that it is wet compared to some other animal, or compared to itself at another time, not that it is as wet as water. No animal is as dry as earth, cold as ice, or hot as fire. According to Galen all things could be quantitatively compared by way of the four fundamental qualities: “Now, since the median in any genus—but especially in that of substance as a whole—consists in a mixing together of the extremes, our conception and identification of it must also come about from the same starting-point. Conceptually the matter is very simple. We begin with the hottest of all perceptible things, fire, say, or violently boiling water, and draw a line from that down to the coldest substance we know, ice, say, or snow; and we mark this line exactly in the middle. This will give us the point of good proportion conceptually—that which is equidistant from each of the extremes. We may also create it physically, by mixing equal amounts of ice and boiling water. For that which is made from a mixture of both of these will be equidistant from the two extremes of burning and of dying of cold. It is thus a simple matter, by getting hold of this mixture, to have an example of the median state of all substance with regard to the opposition of hot and cold. One may then remember this, and use it as a yardstick against which to measure everything else.” Galen says that “ants are dry as animals, while worms are wet; then again, among worms, some are wetter, either just wetter for a worm, or by comparison with some particular worm.” Dogs are wetter than ants or bees, he says, and humans are wetter than dogs. Aristotle's On the Parts of Animals, from about half a millennium before Galen's Mixtures, says tissues, or “homogeneous" parts, must have diverse properties in order to give rise to the diverse functions of organs, the “heterogeneous" parts, including, as examples, arms, lungs, and faces. "For some purposes softness is advantageous, for others hardness; some parts must be capable of extension, others of flexion. Such properties, then, are distributed separately to the different homogeneous parts, one being soft another hard, one fluid another solid, one viscous another brittle; whereas each of the heterogeneous parts presents a combination of multifarious properties" (Aristotle and Ogle 1882). He considered the duality fluid/solid to have special significance: “Now there are three degrees of composition; and of these the first in order, as all will allow, is composition out of what some call the elements, such as earth, air, water, fire. Perhaps, however, it would be more accurate to say composition out of the elementary forces; nor indeed out of all of these, but out of a limited number of them, as defined in previous treatises. For fluid and solid, hot and cold, form the material of all composite bodies; and all other differences are secondary to these, such differences, that is, as heaviness or lightness, density or rarity, roughness or smoothness, and any other such properties of matter as there may be.” A body's status in terms of hot and cold and solid and fluid is seen as a major determinant of life and death. Aristotle says the balance of these things is responsible for sleep, health, and aging (Aristotle and Ogle 1882). He was partially mistaken in his description of the brain, calling it a cold, bloodless, excrement-resembling concoction of earth and water not connected to the rest of the body or the senses. He assigned the brain the function of moderating the heat of the heart and soul, holding the body in the perfect balance. He refers in other places to the brain as a fluid and to its superabundant fluidity, and in others again to its solidness. As organs go, it seems, the brain is difficult to place in a solid or fluid category. Peter Mark Roget wrote in Animal and Vegetable Physiology: “The animal as well as the vegetable fabric is necessarily composed of a union of solid and fluid parts. Every animal texture appears to be formed from matter that was originally in a fluid state; the particles of which they are composed having been brought together and afterwards concreting by a process, which may, by a metaphor borrowed from physical science, be termed crystallization. Many of those animals, indeed, which occupy the lowest rank in the series, such as Medusae, approach nearly to the fluid state; appearing like a soft and transparent jelly, which, by spontaneous decomposition after death, or by the application of heat, is resolved almost wholly into a limpid watery fluid. More accurate examination, however, will show that it is in reality not homogeneous, but that it consists of a large proportion of water, retained in a kind of spongy texture, the individual fibres of which, from their extreme fineness and uniformity of distribution, can with difficulty be detected. Thus even those animal fabrics, which on a superficial view appear most simple, are in reality formed by an extremely artificial and complex arrangement of parts. The progress of development is continually tending to solidify the structure of the body” (1867). American naturalist John Burroughs addresses solidness and fluidity in a chapter called “The Living Wave” of his book The Breath of Life: “It is a significant fact that the four chief elements which in various combinations make up living bodies are by their extreme mobility well suited to their purpose. Three of these are gaseous; only the carbon is solid. This renders them facile and adaptive in the ever-changing conditions of organic evolution. The solid carbon forms the vessel in which the precious essence of life is carried. Without carbon we should evaporate or flow away and escape. Much of the oxygen and hydrogen enters into living bodies as water; nine tenths of the human body is water; a little nitrogen and a few mineral salts make up the rest. So that our like in its final elements is little more than a stream of water holding in solution carbonaceous and other matter and flowing, forever flowing, a stream of fluid and solid matter plus something else that scientific analysis cannot reach—some force or principle that combines and organizes these elements into the living body. If a man could be reduced instantly into his constituent elements we should see a pail or two of turbid fluid that would flow down the bank and soon be lost in the soil. That which gives us our form and stability and prevents us from slowly spilling down the slope at all times is the mysterious vital principle of force which knits and marries these unstable elements together and raises up a mobile but more or less stable form out of the world of fluids” (Burroughs 1915).


Liquid crystallinity


Works cited


Aristotle, and William Ogle. Aristotle on the Parts of Animals. Translated, with Introduction and Notes, by W. Ogle. Kegan Paul & Co, 1882.


Burroughs, John. “The Breath of Life.” Boston: Houghton Mifflin, 1915, doi:10.5962/bhl.title.30417.


Galen, and Peter N. Singer. Galen: Works on Human Nature Volume 1, Mixtures (De Temperamentis). Oxford University Press, 1997.


Haeckel, Ernst. The Wonders of Life: A Popular Study of Biological Philosophy. Trans. Joseph McCabe. London: Watts and Co., 1904.


Leslie, Esther. Liquid Crystals: the Science and Art of a Fluid Form. Reaktion Books, 2016.


Ovid. “Metamorphoses.” Trans. Charles Martin. Western Literature: The Norton Anthology. Vol. 1. 8th ed. Ed. Sarah Lawall. New York: Norton, 2006.


Roget, Peter Mark. Animal and Vegetable Physiology, Considered with Reference to Natural Theology. Volume 1. London: Carey, Lea & Blanchard, 1840.

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