Aristotle’s Physics: the Five Elements

How would Aristotle have used computer graphics to depict his ideas about the Five Elements?

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Abstract

Aristotle wrote his Physics and his Meteorology ca. 350 BC. Although they appear primitive by our 21st Century scientific lights, they capture the wisdom of the ages. Aristotle, in his time, may have used diagrams when discussing the Five Elements, but all that survives is his prose. The plain text is inadequate for modern understanding so I created some graphics that explain his concepts more clearly to a contemporary audience.

Introduction

Aristotle’s writings date from over 2300 years ago. They include many books chock full of wondrous ideas. This Knol presents and interprets the Five Elements (Aether, Air, Fire, Water, and Earth). 
 
The computer graphics in this Knol approach the topic from a “practical engineering viewpoint”. They should give the reader a clear and satisfying concept of what I think Aristotle was getting at. It is what I think Aristotle would say if he was privy to our modern scientific understanding and word usage and had access to computer graphics!
 
Like me, you may find philosophy hard to understand. As my PhD advisor told me, philosophers make simple things complex, using a language specially created for that purpose! 
 
You have undoubtedly heard about “the five elements” of the ancient philosophers. I couldn’t understand how the ancients thought Fire was a basic element, or that the essence of Air was wet or of Water cold. It turns out they were not using these words according to the literal, narrow scientific meanings we employ. They were thinking about what we would now call the qualities of “energy” and “fluidity”. They used Air, Fire, Water, and Earth as examples of things that had a lot or a little energy and/or fluidity.
 
Modern scientists dismiss the concept of Aether out of hand. However, the idea of a non-material substrate is important if we want to understand what the most intelligent and well-informed humans of two millenia ago were thinking. (If modern string theory, which says there are ten or eleven dimensions of which humans may comprehend only four, holds up to scientific examination, it may turn out that the six or seven “tightly curled up” dimensions we humans cannot comprehend might be what the ancients called the Aether!)
 
OK, let’s give Aristotle access to modern computer graphics and the world of Google Knols and see where that takes us!
 

The Five Elements

Aether – The Quintessence, The First Element, The All

Aether is the perfect element that fills the cosmos and the terrestrial sphere. In the heavens it is the quintessence, absolutely pure and fit for the gods. From the moon down to the terrestrial sphere, it is the invisible substratum for the other four elements. By its nature, Aether is neither dry nor wet, hot nor cold. It is not subject to change and moves in perfect circles.

 
“… the first element … the whole world of the upper motions is full of that body. … the word Aether has long been used to denote that element.” [Aristotle, Meteorology, Book I,Part 1. In this and subsequent quotes from the MIT Internet Classics Archive, I have changed “ether” to “Aether” and used initial capitalization and bold font for the Five Elements: Aether, Fire, Air, Water, Earth.]
 

Terrestrial Elements – Air, Fire, Water and Earth

Air, Fire, Water, and Earth are the terrestrial elements (“simple bodies” in Aristotle’s words) that we humans experience. By their nature, they move in straight lines and are subject to change. They share a double dichotomy of qualities: Hot/Cold and Wet/Dry.
 
Each element has a primary quality plus a secondary one:  
Air is Wet and also Hot. It is best to think of Air and its primary quality (Wet) as the zenith or ultimate in fluidity (not simply as the mixture of nitrogen, oxygen and trace gasses in our literal definition).
Fire is Hot and also Dry. It is best to think of Fire and its primary quality (Hot) as the zenith or ultimate in energy (not simply the product of combustion of fuel and oxygen in our literal definition).
Water is Cold and also Wet. It is best to think of Water and its primary quality (Cold) as the nadir or minimum in energy.
Earth is Dry and also Cold. It is best to think of Earth and its primary quality (Dry) as the nadir or minimum in fluidity.
All terrestrial materials are composed of varying rarity or density of each of the Four Elements, carried on the invisible, unsensible substrate of the Aether. Thus, light materials contain a high proportion of Air and some Fire, combustible materials contain a high proportion of Fire and some Earth, solid materials a high proportion of Earth and some Water, and heavy materials a high proportion of Water and some Air.
  
“… Fire, Air, Water, Earth, we assert, originate from one another, and each of them exists potentially in each, as all things do that can be resolved into a common and ultimate substrate [the Aether]. … [Aristotle, Meteorology, Book I,Part 1]
“… Fire, Earth, Air, and Water are … involved with pairs of contraries [Aristotle, Physics, Book I, Part 6]
 

Energy – Hot/Cold Contrarities

As noted above, Fire is primarily Hot and Water primarily Cold. Air is secondarily Hot and Earth secondarily Cold. What Aristotle referred to as the Hot and Cold contrarities are more properly regarded as different density and rarity of energy. The chart above indicates the progression from Cold Water and Earth to Hot Air and Fire as energy density increases. 
 
Common terrestrial items are arranged in the chart according to their standing along the increasing energy scale.  Open flame is high on that scale as are coal and petroleum and other fuels that release energy when ignited. Living things tend towards the middle of the scale. Ice and water are near the bottom, along with metals such as gold, bronze and iron.
 
The items are arranged horizontally according to their fluidity, the “Wet/Dry” contrarity that is described in the following section. The materials consitituing the items depicted in the chart are mixtures containing different proportions of Fire, Air, Earth and Water. The more Fire and Air they contain, and correspondingly less Earth and Water, the higher their energy and vice-versa.
 
“… Of things that exist, some exist by nature, some from other causes. … ‘By nature’ the animals and their parts exist, and the plants and the simple bodies (Earth, Fire, Air, Water)-for we say that these and the like exist ‘by nature’. …But if the material of each of these objects has itself the same relation to something else, say bronze (or gold) to Water, bones (or wood) to Earth and so on, that (they say) would be their nature and essence. Consequently some assert Earth, others Fire or Air or Water or some or all of these, to be the nature of the things that are.” [Aristotle, Physics, Book II, Part 1]
 

Fluidity – Wet/Dry Contrarities

As noted above, Air is primarily Wet and Earth primarily Dry. Water is secondarly Wet and Fire secondarily Dry. What Aristotle referred to as the Wet and Dry contrarities are more properly regarded as different density and rarity of fluidity. The chart above indicates the progression from Wet Air and Water to Dry Fire and Earth as fluidity increases. 

 
Common terrestrial items are arranged in the chart according to their standing along the increasing fluidity scale.  Air is high on that scale as are Water and liquid fuels that readily flow according to their nature. Air flows upwards and Water downwards. Living things tend towards the middle of the scale. Ice and flame are near the bottom, along with metals such as gold, bronze and iron.
 
The items are arranged horizontally according to their energy, the “Hot/Cold” contrarity described in the previous section. The materials consitituing the items depicted in the chart are mixtures containing different proportions of Air, Water, Fire and Earth. The more Air and Water they contain, and correspondingly less Fire and Earth, the higher their fluidity and vice-versa.
 

Selected Quotations in Context

I’ve shortened the quotations that appear above to highlight their essential message. They appear below in longer form. The quotes are from the MIT Internet Classics Archive I have changed “ether” to “Aether“, used initial capitalization and bold font for the Five Elements: Aether, Fire, Air, Water, Earth, and added clarifications in [brackets].
 

Meteorology, Book I 

 
From Part 1. About the origin of the five elements.
 
Fire, Air, Water, Earth, we assert, originate from one another, and each of them exists potentially in each, as all things do that can be resolved into a common and ultimate substrate [the Aether]. …

What are we to take its nature to be in the world surrounding the earth? … The question is really about that which lies between the earth and the nearest stars. Are we to consider it to be one kind of body or more than one? And if more than one, how many are there and what are the bounds of their regions?

We have already described and characterized the first element [the Aether], and explained that the whole world of the upper motions is full of that body.

This is an opinion we are not alone in holding: it appears to be an old assumption and one which men have held in the past, for the word Aether has long been used to denote that element.

 
From Part 2.  The Aether makes up the system of bodies that move in a circle in the heavens. The four simple bodies or elements that owe their existence to the four principles (Dry/Wet, Hot/Cold) are Fire, Air, Water, and Earth.

We have already laid down that there is one physical element which makes up the system of the bodies that move in a circle [the Aether], and besides this four bodies [elements] owing their existence to the four principles, the motion of these latter bodies being of two kinds: either from the centre [up] or to the centre [down]. These four bodies are Fire, Air, Water, Earth. Fire occupies the highest place among them all, Earth the lowest, and two elements correspond to these in their relation to one another, Air being nearest to Fire, Water to Earth. The whole world surrounding the Earth, then, the affections of which are our subject, is made up of these bodies [elements]. This world necessarily has a certain continuity with the upper motions: consequently all its power and order is derived from them. (For the originating principle of all motion is the first cause. Besides, that element is eternal and its motion has no limit in space, but is always complete; whereas all these other bodies have separate regions which limit one another.) So we must treat Fire and Earth and the elements like them as the material causes of the events in this world (meaning by material what is subject and is affected), but must assign causality in the sense of the originating principle of motion to the influence of the eternally moving bodies.
 
From Part 3. What is between the Earth and heavenly bodies? Aristotle says it is Air and a kind of Fire (but he says it is not really Fire) and Water-vapor, along with the Aether. These fill the space beween the Earth and the moon, From the moon up to the heavenlybodies it is pure Aether
 
This excerpt includes an ingenious “proof” that the sun and the other stars are not inherently hot (i.e., not made of Fire). The heat we sense from the sun is actually caused by its friction as it passes through the Aether. We get heat from the movement of the stars as well, but not as much because they are much further away than the sun. We also get heat from the moon, but not as much because it is moving more slowly than the sun because the sun circles daily, the moon monthly.

Let us first recall our original principles and the distinctions already drawn and then explain the ‘milky way’ and comets and the other phenomena akin to these.

Fire, Air, Water, Earth, we assert, originate from one another, and each of them exists potentially in each, as all things do that can be resolved into a common and ultimate substrate.

The first difficulty is raised by what is called the Air. What are we to take its nature to be in the world surrounding the Earth? And what is its position relatively to the other physical elements. (For there is no question as to the relation of the bulk of the Earth to the size of the bodies which exist around it, since astronomical demonstrations have by this time proved to us that it is actually far smaller than some individual stars. As for the Water, it is not observed to exist collectively and separately, nor can it do so apart from that volume of it which has its seat about the Earth: the sea, that is, and rivers, which we can see, and any subterranean Water that may be hidden from our observation.) The question is really about that which lies between the Earth and the nearest stars. Are we to consider it to be one kind of body or more than one? And if more than one, how many are there and what are the bounds of their regions?

We have already described and characterized the first element [Aether], and explained that the whole world of the upper motions is full of that body.

This is an opinion we are not alone in holding: it appears to be an old assumption and one which men have held in the past, for the word Aether has long been used to denote that element. Anaxagoras, it is true, seems to me to think that the word means the same as Fire. For he thought that the upper regions were full of Fire, and that men referred to those regions when they spoke of Aether. In the latter point he was right, for men seem to have assumed that a body that was eternally in motion was also divine in nature; and, as such a body was different from any of the terrestrial elements, they determined to call it ‘Aether’.

For the um [sic] opinions appear in cycles among men not once nor twice, but infinitely often.

Now there are some who maintain that not only the bodies in motion but that which contains them is pure Fire, and the interval between the Earth and the stars Air: but if they had considered what is now satisfactorily established by mathematics, they might have given up this puerile opinion. For it is altogether childish to suppose that the moving bodies are all of them of a small size, because they so [appear] to us, looking at them from the Earth.

This a matter which we have already discussed in our treatment of the upper region, but we may return to the point now.

If the intervals were full of Fire and the bodies consisted of Fire every one of the other elements would long ago have vanished.

However, they cannot simply be said to be full of Air either; for even if there were two elements to fill the space between the Earth and the heavens, the Air would far exceed the quantity required to maintain its proper proportion to the other elements. For the bulk of the Earth (which includes the whole volume of Water) is infinitesimal in comparison with the whole world that surrounds it. Now we find that the excess in volume is not proportionately great where Water dissolves into Air [clouds, steam] or Air into Fire [smoke]. Whereas the proportion between any given small quantity of Water and the Air that is generated from it ought to hold good between the total amount of Air and the total amount of Water. Nor does it make any difference if any one denies that the elements originate from one another, but asserts that they are equal in power. For on this view it is certain amounts of each that are equal in power, just as would be the case if they actually originated from one another.

So it is clear that neither Air nor Fire alone fills the intermediate space.

It remains to explain, after a preliminary discussion of difficulties, the relation of the two elements Air and fire to the position of the first element [Aether], and the reason why the stars in the upper region impart heat to the Earth and its neighbourhood. Let us first treat of the Air, as we proposed, and then go on to these questions.

Since Water is generated from Air, and Air from Water, why are clouds not formed in the upper Air? They ought to form there the more, the further from the Earth and the colder that region is. For it is neither appreciably near to the heat of the stars, nor to the rays relected from the Earth. It is these that dissolve any formation by their heat and so prevent clouds from forming near the Earth. For clouds gather at the point where the reflected rays disperse in the infinity of space and are lost. To explain this we must suppose either that it is not all Air which Water is generated, or, if it is produced from all Air alike, that what immediately surrounds the Earth is not mere Air, but a sort of vapour, and that its vaporous nature is the reason why it condenses back to Water again. But if the whole of that vast region is vapour, the amount of Air and of Water will be disproportionately great. For the spaces left by the heavenly bodies must be filled by some element. This cannot be Fire, for then all the rest would have been dried up. Consequently, what fills it must be Air and the Water that surrounds the whole Earth-vapour being Water dissolved.

After this exposition of the difficulties involved, let us go on to lay down the truth, with a view at once to what follows and to what has already been said. The upper region as far as the moon we affirm to consist of a body distinct both from Fire and from Air, but varying degree of purity and in kind, especially towards its limit on the side of the Air, and of the world surrounding the Earth. Now the circular motion of the first element and of the bodies it contains dissolves, and inflames by its motion, whatever part of the lower world is nearest to it, and so generates heat. From another point of view we may look at the motion as follows. The body that lies below the circular motion of the heavens is, in a sort, matter, and is potentially Hot, Cold, Dry, Wet, [the double dichotomy of contrarities] and possessed of whatever other qualities are derived from these. But it actually acquires or retains one of these in virtue of motion or rest, the cause and principle of which has already been explained. So at the centre and round it we get Earth and Water, the heaviest and coldest elements, by themselves; round them and contiguous with them, Air and what we commonly call Fire. It is not really Fire, for Fire is an excess of heat and a sort of ebullition [boiling, violent outpouring]; but in reality, of what we call Air, the part surrounding the Earth is moist and warm, because it contains both vapour and a dry exhalation from the Earth. But the next part, above that, is warm and dry. For vapour is naturally moist and cold, but the exhalation warm and dry; and vapour is potentially like Water, the exhalation potentially like Fire. So we must take the reason why clouds are not formed in the upper region to be this: that it is filled not with mere Air but rather with a sort of Fire.

However, it may well be that the formation of clouds in that upper region is also prevented by the circular motion. For the Air round the Earth is necessarily all of it in motion, except that which is cut off inside the circumference which makes the Earth a complete sphere. In the case of winds it is actually observable that they originate in marshy districts of the Earth; and they do not seem to blow above the level of the highest mountains. It is the revolution of the heaven which carries the Air with it and causes its circular motion, Fire being continuous with the upper element and Air with Fire. Thus its motion is a second reason why that Air is not condensed into Water.

But whenever a particle of Air grows heavy, the warmth in it is squeezed out into the upper region and it sinks, and other particles in turn are carried up together with the fiery exhalation. Thus the one region is always full of Air and the other of Fire, and each of them is perpetually in a state of change.

So much to explain why clouds are not formed and why the Air is not condensed into Water, and what account must be given of the space between the stars and the Earth, and what is the body [Aether] that fills it.

As for the heat derived from the sun, the right place for a special and scientific account of it is in the treatise about sense, since heat is an affection of sense, but we may now explain how it can be produced by the heavenly bodies which are not themselves hot.

We see that motion is able to dissolve and inflame the Air; indeed, moving bodies are often actually found to melt [friction]. Now the sun’s motion alone is sufficient to account for the origin of terrestrial warmth and heat. For a motion that is to have this effect must be rapid and near, and that of the stars is rapid but distant, while that of the moon is near but slow, whereas the sun’s motion combines both conditions in a sufficient degree. That most heat should be generated where the sun is present is easy to understand if we consider the analogy of terrestrial phenomena, for here, too, it is the Air that is nearest to a thing in rapid motion which is heated most. This is just what we should expect, as it is the nearest Air that is most dissolved by the motion of a solid body.

This then is one reason why heat reaches our world. Another is that the Fire surrounding the Air is often scattered by the motion of the heavens and driven downwards in spite of itself.

Shooting-stars further suffix to prove that the celestial sphere is not hot or fiery: for they do not occur in that upper region but below: yet the more and the faster a thing moves, the more apt it is to take Fire [by friction]. Besides, the sun, which most of all the stars is considered to be hot, is really white and not fiery in colour. 

 

Physics, Book I 

 
From Part 1. Principles of the science of Nature.
Plainly therefore in the science of Nature, as in other branches of study, our first task will be to try to determine what relates to its principles…
 
From Part 5. The primary contrarities – the first two principles. Aristotle, or the translators, seem to use the word “principles” in different ways in Physics and Meteorology, and count their number in an inverse manner. Here in Physics there are two principles, rarity and density, and two contrarities, Hot/Cold and Wet/Dry. (In modern scientific terms, Hot/Cold are the contrary states of density and rarity of energy. Wet/Dry are the contrary states of density and rarity of fluidity.) Then there is a third principle, Aether. In Meteorology (see the previous section) Aristotle says the first princile is Aether. Then there are four terrestrial principles (and elements or “simple bodies”) that appear to be Hot/Fire, Cold/Water, Wet/Air, and Dry/Earth.
 
For first principles must not be derived from one another nor from anything else, while everything has to be derived from them. But these conditions are fulfilled by the primary contraries [such as rarity and density], which are not derived from anything else because they are primary, nor from each other because they are contraries….
 
From Part 6. Why we need a third principle (the All or Aether).
… [I]t is plausible to suppose … more than two [principles]. For it is difficult to see how either density should be of such a nature as to act in any way on rarity or rarity on density. The same is true of any other pair of contraries … but both [contraries] act on a third thing different from both [the substratum, i.e., the Aether].

[It is] necessary to assume a third principle as a substratum [because] (1) We do not find that the contraries constitute the substance of any thing. … (2) we hold that a substance is not contrary to another substance. How then can substance be derived from what are not substances? Or how can non-substances be prior to substance?

… [W]e must … assume a third somewhat as the substratum of the contraries, such as is spoken of by those who describe the All [note the upper case “A” – the All is the Aether] as one nature-Water or Fire or what is intermediate between them. What is intermediate seems preferable; for Fire, Earth, Air, and Water are already involved with pairs of contraries [Hot/Cold and Wet/Dry]. There is, therefore, much to be said for those who make the underlying substance different from these four; …  Indeed this doctrine too (that the One and excess and defect are the principles of things) would appear to be of old standing, though in different forms; for the early thinkers made the two the active and the one the passive principle, whereas some of the more recent maintain the reverse.  

“In another sense (2) the form or the archetype, i.e. the statement of the essence, and its genera, are called [the Formal] ’causes’ (e.g. of the octave the relation of 2:1, and generally number), and the parts in the definition.
 

Physics, Book II  

From Part 1. The terrestrial elements or “simple bodies”, Earth, Fire, Air, and Water, exist by nature.
Of things that exist, some exist by nature, some from other causes.
 
‘By nature’ the animals and their parts exist, and the plants and the simple bodies (Earth, Fire, Air, Water) -for we say that these and the like exist ‘by nature’. …
 
But if the material of each of these objects has itself the same relation to something else, say bronze (or gold) to Water, bones (or wood) to Earth and so on, that (they say) would be their nature and essence. Consequently some assert Earth, others Fire or Air or Water or some or all of these, to be the nature of the things that are.

Physics, Book IV   

From Part 1.  The existence of place. Each element is naturally carried to its own place.
 
The existence of place is held to be obvious from the fact of mutual replacement. Where Water now is, there in turn, when the Water has gone out as from a vessel, Air is present. When therefore another body occupies this same place, the place is thought to be different from all the bodies [elements] which come to be in it and replace one another. What now contains Air formerly contained Water, so that clearly the place or space [Aether] into which and out of which they passed was something different from both.

Further, the typical locomotions of the elementary natural bodies-namely, Fire, Earth, and the like-show not only that place is something, but also that it exerts a certain influence. Each is carried to its own place, if it is not hindered, the one [AIr, Fire] up, the other [Water, Earth] down. Now these are regions or kinds of place-up and down and the rest of the six directions. Nor do such distinctions (up and down and right and left, &c.) hold only in relation to us. To us they are not always the same but change with the direction in which we are turned: that is why the same thing may be both right and left, up and down, before and behind. But in nature each is distinct, taken apart by itself. It is not every chance direction which is ‘up’, but where Fire and what is light are carried; similarly, too, ‘down’ is not any chance direction but where what has weight and what is made of Earth are carried-the implication being that these places do not differ merely in relative position, but also as possessing distinct potencies.