Philosophical Principles on Matter and Movement, Denis Diderot

Avertissement du Traducteur - December 2010

This is my rendering into English of Denis Diderot's sketch (1770) of a materialist philosophy built upon discursive moves away from conceiving force as acting upon particles rather than coming from particles themselves. This conception goes further than previous philosophical programs in offering a vision that adequately removes teleology from physics, even if it still includes purpose in the material world by giving this world its own sufficient laws.

With this impetus then, who is to say how many forces there are in the universe? Indeed, a hurricane fills air with power, heating a tube of glass makes gold leaves flutter - so why not conceive of a plurality of forces in the universe rather than gravity alone? Perhaps such a view paves the way for a scientific poetics in that each new presentation of scientific findings is not one more triumph in the modern labor of describing the nth-millionth variation on gravitation. Even a new scientific model that seems destined to only raise Newton above the shoulders of others might be understood as emerging from very particular crumbs from which it had previously been destined to be elevated only by Newtonian Gravity.

NOTE: This is a translation made more for the purpose of familiarizing myself with Diderot's text. It is updated often, especially when insights about how to render certain passages strike me. I also hope to offer a "reading" in the form of annotations/footnotes soon.

I don't know in what sense philosophers have supposed that matter has been indifferent to movement and to rest. What is very certain is that all bodies gravitate upon each other, that all particles of bodies gravitate upon each other, that in this universe, all is in translation or endeavor (nisu), or in translation and in endeavor (in nisu) at once.

This supposition of philosophers resembles those of geometers who admit points without any dimension, lines without length or depth, surfaces without thickness, or perhaps they speak of rest of one mass relative to another. Everything is in relative rest in a vessel beaten by a storm. Nothing is in absolute rest, not even aggregate molecules, nor this vessel, nor the body that it encloses.

Even if they do not conceive of a tendency to rest more than movement in any body, they look at matter as homogenous. They make an abstraction from all of its essential qualities; they consider it inalterable in the instant almost indivisible from their speculation. They leap from relative rest of one aggregate to another aggregate; they forget, while proceeding from the inertness of a body to movement or to rest, that a block of marble tends toward its dissolution. They annihilate matter with thought and generalized movement that animates all bodies, and a particular action of one upon another, which destroys them all. This is how inertness, false in itself, is but temporary, and has not made laws of movement erroneous.

The body, according to some philosophers, is in itself, without action and without force. This is a terrible falsity, quite contrary to all valid physics, to all valid chemistry. By itself, by the nature of its essential qualities, whether considered as a molecule or as a mass, it is full of action and force.

For you to represent movement, they add, in addition to existing matter, it is necessary for you to imagine a force which should act on this matter. Not so. A molecule endowed with but one quality for its nature is an active force in itself. It exercises itself upon another molecule, exercised upon it. All these paralogisms maintain the false supposition of homogeneous matter. You who imagine matter at rest just the same, can you imagine fire at rest? Everything in nature has a different action, as does this heap of molecules you call fire. In this heap you call fire, each molecule has a nature, an action.

Here is the true difference between rest and movement: absolute rest is an abstract concept that does not exist in nature, and movement is a quality as real as length, width, and depth. Am I concerned with what you think? Do I hope you look at matter as homogeneous or heterogeneous? Do I expect that, creating an abstraction of its qualities and only considering its existence, you see it in rest? Do I care that you search, as a result, for one cause that moves it? Do what you please with geometry and metaphysics. Yet, I who am a natural scientist and chemist, who works with bodies in nature and not from my head, I see them existing, varied, adorned by properties and actions and acting in the universe as in the laboratory - where one spark is no longer found beside three molecules combined with saltpeter, carbon, and sulfur, without a necessary explosion following.

Gravity is not a tendency to rest, it is a tendency to local movement.

So that matter may move, it is said further, that an action, a force is necessary. Yes, a force external to the molecule, or inherent to, essential to, or engaged with this molecule, constituting its nature from an igneous, aqueous, nitrous, alkaline, or sulfurous molecule. Regardless of this nature, force results, with action from it outside of it, and action of other molecules upon it.

Force acting on a molecule exhausts itself. Inner force of the molecule does not. It is immutable, eternal. These two forces can produce two types of endeavors (nisus). The first, endeavor (nisus) that ends; the second, endeavor (nisus) that never ends. It is therefore absurd to say that matter has a real opposition to movement.

Quantity of force is constant in nature, but the sum of endeavors (nisus) and the sum of translations are variable. The greater the sum of endeavors (nisus), the smaller the sum of translations; the greater the sum of translations, the smaller the sum of endeavors (nisus). The incineration of a city suddenly grows the sum of translations with a prodigious quantity.

One atom moves the world. Nothing is more true - except an atom moved by the world. Since the atom has its own force, it cannot be without effect.

As a natural scientist we must never say, "a body is a body", because we are no longer doing natural science. This is to make abstractions that lead to nothing.

We must not confound action with mass. There can be great mass and small action. There can be small mass and great action. One molecule of air might shatter a block of steel. Four grains of powder are sufficient for dividing a rock.

Yes, without a doubt, when an homogeneous aggregate is compared to another aggregate of similar homogeneous matter, when we speak of action and reaction of these two aggregates, their relative energies are in direct relation to mass. But when it is a matter of heterogeneous aggregates, there are no longer the same laws. There are as many different laws as there are varieties of force intertwined with each elementary molecule and constitutive of bodies.

The body is resistant to horizontal movement. What does that mean? It is well known that there is a force general and common to all molecules of the globe we inhabit, a force which pushes against bodies according to a certain perpendicular direction, or much the same, along the surface of the globe. But this general and common force is contradicted by a hundred thousand others. Heating a tube of glass makes gold leaves flutter. A hurricane fills air with power. Heat volatilizes water; volatilized water carries with it, molecules of salt. While this mass of bronze weighs against the ground, air acts on it, changing its initial surface into a metallic chalk, beginning the destruction of this body. What I say of masses must be understood of molecules also.

Every molecule must be considered as currently animated by three types of actions: the action of gravity or gravitation, the action of its force intertwined with its water, fire, air, sulfur nature, and the action on it of all other molecules. It could also be that these three actions would be convergent or divergent. Convergent, then the molecule is endowed with its strongest possible action. In order to give an idea of the greatest possible action, it would be necessary to thus say, to give a bunch of absurd suppositions, to place a molecule in a totally metaphysical situation.

How can one say that a body resists more through movement the greater its mass? Not in the sense that the more its mass is great, the more its pressure against an obstacle is weak. No daily laborer (crocheteur) knows the contrary. It's only relative to one direction opposite its pressure. In this direction, it is certain that it resists as much through its movement the greater its mass. In the direction of gravity, it's not less certain that its pressure or force, or tendency to movement, grows in relation to its mass. What then does all this signify? Nothing.

I am surprised to see a body fall no more than to see flame raise itself up, or to see water act all over and to weigh in on its height and its base in such a way that with a mediocre quantity of fluid, I can break the most solid vessels, just as one sees expanding steam dissolve the hardest bodies in Papin's machine, and raise the heaviest bodies in a pneumatic machine (la machine à feu). But I fix my eyes on the universal mass of bodies: I see everything in action and reaction; everything being destroyed under one form, everything being recomposed under another: sublimations, dissolutions, combinations of all types, phenomena incompatible with a homogeneity of matter, from which I conclude that it is heterogeneous, that an infinity of different elements exist in nature, that each of these elements by its diversity has its individual force, innate, immutable, eternal, indestructible, and that these interconnected forces in the body have actions outside of the body, from which arises movement, or rather universal fermentation in the universe.

What do the philosophers of whom I refute here, the errors and paralogisms, do? They attach themselves to a single and unique force, perhaps, common to all the molecules of matter; I say, perhaps, because I would not be surprised if there should be in nature, such a molecule which, joined to another, rendered the resulting mixture lighter. Always in the laboratory, an inert body is volatilized by an inert body. And when those who consider all action in the universe only as that of gravitation, in having inferred inertness from matter to rest or movement, or rather, the tendency of matter to rest, they believe to have resolved the question, when they have not even grazed it.

When the body is viewed at as more or less resistant, and not as weighing or tending towards a center of graves(1), a force may already be recognized, an inner, intertwined action. It has many others however, among which some exert themselves all over, and others take particular directions.

The supposition of a any kind of being placed outside the material universe is impossible. We must never suppose likewise, because one can never infer anything from such suppositions.

Everything said of the impossibility of the growth of movement or of speed, suavely goes against the hypothesis of homogenous matter. But what is this fact to those who infer movement in matter, from its heterogeneity? The supposition of a homogenous matter is strongly subject to other absurdities.

If one insists not on considering things in one's head, but in the universe, one will convince oneself by the diversity of phenomena, the diversity of elementary matter, the diversity of forces, the diversity of actions and of reactions, the necessity of movement. And for all these accepted truths, one says no more, "I see matter as existing; I see it first of all at rest"; because one will sense that this is to make an abstraction from which one can conclude nothing. Existence draws along neither rest nor movement; but existence is not the only quality of rest.

All natural scientists who suppose matter indifferent to movement and to rest, have no clear ideas of resistance. In order that they may conclude something of resistance, it would be necessary that this quality should be exercised indistinctly, all over, and that its energy were equal in every direction. This would then be an inner force, like that of every molecule, but this resistance varies to the same degree that there are directions in which the body can be pushed. It is greater vertically than horizontally.

The difference between gravity and the force of inertia: gravity does not equally resist, in all directions, but instead, the force of inertia resists equally, in all directions.

And why would the force of inertia not bring about the effect of retaining the body in its state of rest and in its state of movement, and by the sole notion of resistance proportioned to the quantity of matter[?] The notion of pure resistance is applied equally to rest and to movement: to rest when the body is in movement; to movement, when the body is in rest. Without this resistance, there would be no shock before movement nor would it be stopped after this shock, because the body would be nothing.

In the experiment of the ball suspended by a thread, gravity is destroyed. The ball pulls the thread, as much as the thread pulls the ball. Thus the resistance of bodies comes from a single force of inertia.

If the thread has pulled the ball more than gravity, the ball would ascend. If the ball has been pulled more by gravity than by the thread, it would descend. Etc. Etc.

  1. An archaic term for "gravity". See DPV vol. 17, p. 19, note 14.