_The abstract idea of matter must be decomposed._ Instead of regarding matter as a unique existence, rude, passive, incapable of moving itself, of combining itself, we ought to look upon it as a Kind of existence, of which the various individual members comprising the Kind, in spite of their having some common properties, such as extension, divisibility, figure, etc., still ought not to be ranged in a single class, nor comprised in a single denomination. _What is nature's process? Continual movement._ From the stone which is formed in the bowels of the earth by the intimate combination, as they approach one another, of analogous and similar molecules, up to the sun, that vast reservoir of heated particles that gives light to the firmament; from the numb oyster up to man--we observe an uninterrupted progression, a perpetual chain of combination and movements, from which there result beings that only differ among one another by the variety of their elementary matters, and of the combination and proportion of these elements. From this variety springs an infinite diversity of ways of existing and acting. In generation, nutrition, preservation, we can see nothing but different sorts of matter differently combined, each of them endowed with its own movements, each of them regulated by fixed laws that cause them to undergo the necessary changes. Let us notice here three of the author's definitions. (1.) _Motion is an effort, by which a body changes or tends to change its place._ (2.) Of the ultimate composition of Matter, Holbach says nothing definite, though he assumes molecular movement as its first law. He contents himself, properly enough perhaps in view of the destination of his treatise, with a definition "relatively to us." Relatively to us, then, _Matter in general is all that affects our senses in any fashion whatever; and the qualities that we attribute to different kinds of matter, are founded on the different impressions that they produce on us_. (3.) "When I say that Nature produces an effect, I do not mean to personify this Nature, which is an abstraction; I mean that the effect of which I am speaking is the necessary result of the properties of some one of those beings that compose the great whole under our eyes. Thus, when I say that Nature intends man to work for his own happiness, I mean by this that it is of the essence of a being who feels, thinks, wills, and acts, to work for his own happiness. By Essence I mean that which constitutes a being what it is, the sum of its properties, or the qualities according to which it exists and acts as it does."