The System of Nature (1770)
The cover (Ѻ) to 1795 William Hodgson English translation of Baron d’Holbach’s The System of Nature (1770), showing a woman, possibly symbolic of nature or “mother nature”, unveiling a statur of a second woman, with six breasts, possibly alluding to evolution and or a hidden nature, the first of whom is standing on a Cristian cross, which is shackled to the floor, along with some rosary beads, holy water, a crown, and religious hat of some kind.
In famous publications, The System of Nature: Laws of the Moral and Physical World is a 1770 anonymously-published book by Baron d’Holbach, retrospectively characterized as the first-main and greatest “Atheist’s Bible”, wherein thorough-going, science-based, religion-destroying (or religion-reformulating), materialistic atheism is presented.

Soul | Moving Principle
See also: Soul terminology upgrades
The following are Holbach's views on the soul, which he equates to an historical term embodying the "moving principle" within a human or the "motive principle" that acts within a person:

“Thus, in consequence of man’s reasoning upon false principles, the soul, or moving principle within him, as well as the concealed moving principle of nature, have been made mere chimeras, mere beings of imagination.”
Baron d’Holbach (1770), The System of Nature (§7, pg. 51)

“When it is said, that man is not a free agent, it is not pretended to compare him to a body moved by a simple impulsive cause: he contains within himself causes inherent to his existence; he is moved by an interior organ, which has its own peculiar laws, and is itself necessarily determined in consequence of ideas formed from perceptions resulting from sensations which it receives from exterior objects. As the mechanism of these sensations, of these perceptions, and the manner they engrave ideas on the brain of man, are not known to him; because he is unable to unravel all these motions; because he cannot perceive the chain of operations in his soul, OR the motive principle that acts within him, he supposes himself a free agent; which, literally translated, signifies, that he moves himself by himself; that he determines himself without cause: when he rather ought to say, that he is ignorant how or for why he acts in the manner he does.”
— Baron d’Holbach (1770), The System of Nature (pg. 97)

He continues with the following:

“It is true the soul enjoys an activity peculiar to itself: but it is equally certain that this activity would never be displayed, if some motive or some cause did not put it in a condition to exercise itself: at least it will not be pretended that the soul is able either to love or to hate without being moved, without knowing the objects, without having some idea of their qualities. Gunpowder has unquestionably a particular activity, but this activity will never display itself, unless fire be applied to it; this, nowever, immediately sets it in motion.”
— Baron d’Holbach (1770), The System of Nature (pg. 97)

Here, we see Holbach comparing the activation of the soul or internal moving principle to the activation of the gunpowder the motion that results therefrom, which connect the soul to activation energy; other quotes:

“An organized being may be compared to a clock, which, once broken, is no longer suitable to the use for which it was designed. To say, that the soul shall feel, shall think, shall enjoy, shall suffer, after the death of the body, is to pretend, that a clock, shivered into a thousand pieces, will continue to strike the hour, and have the faculty of marking the progress of time.”
Baron d’Holbach (1770), The System of Nature (pg. 118)

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Anti-chance | Absolute determinism
See main: Holbach’s demon; See also: Laplace’s demon
Holbach, in his §4: “Of the Laws of Motion common to all the Beings of Nature—of Attraction and Repulsion—of Inert Force—of Necessity”, stated the following very-ripe anti-chance (or non-chance) view of a dust storm and a political revolution:

“Two examples will serve to throw the principle here laid down, into light—one shall be taken from physics, the other from morals. In a whirlwind of dust, raised by elemental force, confused as it appears to our eyes, in the most frightful tempest excited by contrary winds, when the waves roll high as mountains, there is NOT a single particle of dust, or drop of water, that has been placed by ‘chance, that has not a cause for occupying the place where it is found; that does not, in the most rigorous sense of the word, act after the manner in which it ought to act; that is, according to its own peculiar essence, and that of the beings from whom it receives this communicated force. A geometrician exactly knew the different energies acting in each case, with the properties of the particles moved, could demonstrate that after the causes given, each particle acted precisely as it ought to act, and that it could not have acted otherwise than it did.

In those terrible convulsions that sometimes agitate political societies, shake their foundations, and frequently produce the overthrow of an empire; there is not a single action, a single word, a single thought, a single will, a single passion in the agents, whether they act as destroyers, or as victims, that is not the necessary result of the causes operating; that does not act, as, of necessity, it must act, from the peculiar essence of the beings who give the impulse, and that of the agents who receive it, according to the situation these agents fill in the moral whirlwind. This could be evidently proved by an understanding capacitated to rate all the action and re-action, of the minds and bodies of those who contributed to the revolution.”

Here, to clarify, firstly we see Holbach jettisoning the Greek chance-based version of atomic theory. Secondly, we note that this sharp passage predates the more famous variant given by Pierre Laplace, aka “Laplace’s demon”, given three years later (1773); Hugh Roberts (1997), in respect to how Percy Shelley, supposedly, read both versions, copying the above Holbach version in his notes, summarizes this as follows: [8]

“Holbach's Systeme de la nature dates from 1770, whereas the paper that contains Laplace's most famous statement of absolute determinism, 'Research on the Integration of Differential Equations with Finite Differences and their use in the Theory of Randomness' (‘Recherches sur I’integration des equations differentielles aux differences finies et sur leur usage dans la theore des hasards’), was read to the Royal Academy in 1773, and published in 1776 (Oeuvres completes, vol. 8). Shelley also refers to Laplace in his notes, and had evidently read his Systeme du monde (Hutchinson, 809).”

Roberts, among others (Ѻ), refer to this as Holbach’s demon or Holbach’s demonic "intelligence". [8] Holbach, following this sharp digression, states the following:

“It may, perhaps, be in the arid plains of Lybia, that are amassed the first elements of a storm or tempest, which, borne by the winds, approach our climate, render our atmosphere dense, and thus operating on the temperament, may influence the passions of a man, whose circumstances shall have capacitated him to influence many others, who shall decide after his will the fate of many nations.”

This, as it is popularly known, in modern terms, has been dubbed the "butterfly effect" by James Gleick (1997).

“Would it not be a thousand times better to depend upon blind matter, upon a nature destitute of intelligence, upon chance, or upon nothing?”
— Baron d’Holbach (1770), The System of Nature (pg. 200) (see: god replacement) [8]

“In seeing the world, we acknowledge a material cause of those phenomena which take place in it; and this cause is nature, of whom the energy is shown to those who study her. Let us not be told, that, according to this hypothesis, we attribute every thing to a ‘blind cause’, to the ‘fortuitous concurrence of atoms’; to ‘chance’. We only call those blind causes, of which we know not the combination, the power, and the laws. We call fortuitous, those effects of which we are ignorant of the causes, and which our ignorance and inexperience prevent us from foreseeing. We attribute to chance, all those effects of which we do not see the necessary connection with their causes. Nature is NOT a blind cause; she does NOT act by chance; NOTHING that she does would ever be fortuitous to him who should know her mode of acting, her resources, and her course. Every thing which she produces is necessary, and is never more than a consequence of her fixed and constant laws; every thing in her is connected by invisible bands (see: bond), and all those effects which we see flow necessarily from their causes, whether we know them or not.”
— Baron d’Holbach (1770), The System of Nature (pg. 234)

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people swimming in river
A photo of a family swimming and or "floating" in the current of the underground fresh water rivers of Xcaret Park (Ѻ), a natural network of channels, i.e. a natural waterpark (Ѻ), which circulate under the Yucatan Peninsula, Mexico.
Fate
Holbach , in his §6: “Of the System of Man’s Free Agency”, citing Seneca, conjoins the following two statements:

“The same necessity which regulates the physical, also regulates the moral world, in which every thing is in consequence submitted to fatality. Man, in running over, frequently without his own knowledge, often in despite of himself, the route which nature has marked out for him, resembles a swimmer who is obliged to follow the current that carries him along: he believes himself a free agent, because he sometimes consents, sometimes does not consent, to glide with the stream, which, notwithstanding, always hurries him forward; he believes himself the master of his condition, because he is obliged to use his arms under the fear of sinking.”
— Baron d’Holbach (1770), The System of Nature (pg. 102)

Fate leads the willing and drags the unwilling.”
Seneca (c.55BC), Epistulae (107.11) (Ѻ); after Cleanthes (c.250BC); cited by Baron d’Holbach (1770) in The System of Nature (pg. 102)

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Life | Animate matter
In respect to how inanimate matter can pass into the state of animate matter, Holbach addresses the issue as such:

“If filings of iron, sulphur, and water be mixed together, these bodies thus capacitated to act on each other, are heated by degrees, and ultimately produce a violent combustion. If flour be wetted with water, and the mixture closed up, it will be found, after some lapse of time, (by the aid of a microscope) to have produced organized beings that enjoy life, of which the water and the flour were believed incapable: it is thus that inanimate matter can pass into life, or animate matter, which is in itself only an assemblage of motion. Reasoning from analogy, which the philosophers of the present day do not hold incompatible, the production of a man, independent of the ordinary means, would not be more astonishing than that of an insect with flour and water.”
— Baron d’Holbach (1770), The System of Nature (pg. 20)

Here, we see Holbach vacillating intelligently on the terms “life” or “animate matter”; gets into the issue of life terminology upgrades. Very good digression, however, for this point in history (see: defunct theory of life).

Stone falling (Holbach)
Holbach on a stone vs human (see: rock vs human) in respect to motion and its two types: motion of mass and internal or concealed motion.
Motion
The following are the key segments, from §2: Of Matter and its Origin, on motion, whether be it a stone or a human:

“When it is said, it is the essence of a stone to fall, it is the same as saying, that its descent, is the necessary effect of its gravity, of its density, of the cohesion of its parts, of the elements of which it is composed. In short, the essence of a being, is its particular, its individual nature.”
— Baron d’Holbach (1770), The System of Nature (pg. 16)

Motion an effect by which a body either changes, or has a tendency to change its position: that is to say, by which it successively corresponds with different parts of space, or changes its relative distance to other bodies.”
— Baron d’Holbach (1770), The System of Nature (pg. 16)

“A cause is a being which puts another in motion, or which produces some change in it. The effect is the change produced in one body by the motion or presence of another.”
— Baron d’Holbach (1770), The System of Nature (pg. 16)

“Those which cannot act on any of our organs, either immediately and by themselves, or mediately, by the intervention of other bodies, exist not for us; since they can neither move us, nor consequently furnish us with ideas: they can neither be known to us, nor of course be judged of by us. To know an object, is to have felt it; to feel it, it is requisite to have been moved by it.”
— Baron d’Holbach (1770), The System of Nature (pg. 16)

Here, to pause, let us reference the following:

“The only thing which can be directly perceived by the senses is force, to which may be reduced light, heat, electricity, sound and all the other things which can be perceived by the senses.”
James Maxwell (1847), age 16 answer to homework exercise for Scottish philosopher William Hamilton (1788-1856) on the properties of matter [6]

“Every force tends to give motion to the body on which it acts; but it may be prevented from doing so by other opposing forces, so that equilibrium results, and the body remains at rest. In this case the force performs no work. But as soon as the body moves under the influence of the force, work is performed.”
Rudolf Clausius (1875), “Mathematical Introduction

This last statement by Clausius, to clarify, is a verbal formulation of the principle of the transmission of work. The gist of these three last quotes seems to be digging around at the social first law of motion, or something to this effect. To continue:

To see, is to have been moved by something acting on the visual organs; to hear, is to have been struck by something on our auditory nerves. In short, in whatever mode a body may act upon is, whatever impulse we may receive from it, we can have no other knowledge of it than by the change it produces in us.”
— Baron d’Holbach (1770), The System of Nature (pg. 16)

From the continual action and re-action [see: third law of motion] of these beings, result a series of causes and effects; or a chain of motion guided by the constant and invariable laws peculiar to each being; which are necessary or inherent to its particular nature—which make it always act or move after a determinate manner.”
— Baron d’Holbach (1770), System of Nature (pg. 16)

Next, Holbach attempts to differentiate between two types of motion:

“Our senses bring us generally acquainted with two sorts of motion in the beings that surround us: the one is the motion of the mass, by which an entire body is transferred from one place to another. Of the motion of this genus we are perfectly sensible.—Thus, we see a stone fall, a ball roll, an arm move, or change its position. The other is an internal or concealed motion, which always depends on the peculiar energies of a body: that is to say, on its essence, or the combination, the action, and re-action of the minute—of the insensible particles of matter, of which that body is composed.”
— Baron d’Holbach (1770), System of Nature (pg. 17)

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Will & Motion
Holbach digs into the ‘will’ in the context of his motion model of things as follows:

“That motion which is excited in a body, that contains within itself the causes of those changes we see it undergo, is called ‘spontaneous’. Then it is said, this body acts or moves by its own peculiar energies. Of this kind is the motion of the man who walks, who talks, who thinks. Nevertheless, if we examine the matter a little closer, we shall be convinced, that, strictly speaking, there is no such thing as spontaneous motion in any of the various bodies of nature; seeing they are perpetually acting one upon the other; that all their changes are to be attributed to the causes, either visible or concealed, by which they are moved. The will of man is secretly moved or determined by some exterior cause that produces a change in him: we believe he moves of himself, because we neither see the cause that determined him, the mode in which it acted, nor the organ that it put in motion.”
— Baron d’Holbach (1770), System of Nature (pg. 17)

This is pretty sharp logic, to say the least; here, again, we recall Maxwell:

“I cannot help thinking about the immediate circumstances which have brought a thing to pass, rather than about any ‘will’ setting them in motion. What is done by what is called myself is, I feel, done by something greater than myself in me.”
James Maxwell (1879), “Comment to Fenton Hort when terminally ill” [7]

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Plato
On Plato, and also of Pythagoras, Holbach is unforgiving:

“Plato, the great creator of chimeras, says that ‘those who admit nothing but what they can see and feel, are stupid and ignorant beings, who refuse to admit the reality of the existence of invisible things’. Our theologians hold the same language to us: our European religions, have visibly been infected with the reveries of the Platonists, which evidently are no more than the result of obscure notions, and of the unintelligible metaphysics of the Egyptian Chaldean, and Assyrian priests, among whom Plato drew up his pretended philosophy. Our theologians, still guided by the enthusiasm of Plato, discourse with their followers only of spirit; intelligent, incorporeal substances; invisible powers; angels; demons of mysterious virtues; supernatural effects; divine inspiration; innate ideas, &c., &c.””
— Baron d’Holbach (1770), The System of Nature (pg. 219)

“Whoever will take the trouble to read the works of Plato and his disciples, such as Proclus, Jamblicus, Plotinus, &c. will find in them almost all the doctrines and metaphysical subtilties of the Christian teleology. Moreover, they will find the origin of the symbols, the rites, the sacraments, in short, of the theurgy, employed in Christian worship, who, as well in their religious ceremonies as in their doctrines, have done no more than follow, more or less faithfully, the road which had been traced out for them by the priests of paganism. With respect to the ancient philosophy, with the exception of that of Democritus and Epicurus, it was, for the most part, a true theosophy, imagined by the Egyptian and Assyrian priests: Pythagoras and Plato have been no more than theologians, filled with enthusiasm, and perhaps with knavery. At least, we find in them a sacerdotal and mysterious mind, which will always indicate, that they seek to deceive or that they are not willing men should be enlightened. It is in nature, and not in theology, that we must draw up an intelligible and true philosophy.”
— Baron d’Holbach (1770), The System of Nature (pg. 220)

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Publication
In c.1768, Baron d’Holbach finished a draft of his The System of Nature, which he showed to Denis Diderot.

In 1770, d'Holbach, after smuggling it across the border into Amsterdam to be published, under a pseudonym (Ѻ), under the name "Jean-Baptiste de Mirabaud", a deceased member of the French Academy of Science, e.g. see the 1795 English translation by William Hodgson (Ѻ), then shipped it back to France, where it debuted anonymously as The System of Nature, soon-to-be-dubbed the “Atheist’s Bible” (Ѻ)(Ѻ); the book was banned and publicly burned. [5]

Initially, of note, the anonymous work was attributed to Helvetius and Honore Mirabeau. [1]

Translation | Issues
Of note, there is a 1795 English translation by William Hodgson (1745-1851) (Ѻ)(Ѻ), an 1820 three-volume mis-aligned theistic-rendering English translation by Samuel Wilkinson, and there is an 1835 (1969/1889) proper atheistic-rendering English translation by American free thinker H.D. Robinson (Ѻ); comparative excerpts from the latter two are shown below, wherein severe translation issues, one of many, are apparent:

Theistic Translation | Wilkinson (1820)
Free Thinker Translation | Robinson (1835)
“Thus, in consequence of man's reasoning upon false principles; of having relinquished the evidence of his senses; the moving principle within him, the concealed author of motion, has been made a mere chimera, a mere being of the imagination.”
— Baron d’Holbach (1770), The System of Nature (§7, pg. #., 1820 Wilkinson translation) [9]
“Thus, in consequence of man’s reasoning upon false principles, the soul, or moving principle within him, as well as the concealed moving principle of nature, have been made mere chimeras, mere beings of imagination.”
— Baron d’Holbach (1770), The System of Nature (§7, pg. 51., 1835 Robinson translation) [1]

Firstly, in short, avoid the Wilkinson translation. Secondly, of note, the 1835 H.D. Robinson translation is subtitled "new and improved edition, with notes by Denis Diderot", but many of the footnotes refer to people and incidents well past the reaction end of Denis Diderot (1713-1784), e.g. mention of the 1829 interactions of Robert Taylor and Richard Carlile. These "notes" then would seem to have been made by Robinson.

Goethe
In 1770-1771, Goethe, as a student at the University of Strasbourg, reacted to the work as follows

“Finally, there is an often-quoted estimate of d'Holbach's work from a very different quarter. In Poetry and Truth (Wahrheit unit Dichtung, Book XI), Goethe speaks of his studies at Strasbourg and remarks that out of curiosity he and his friends had a look at the System of Nature. ‘We could not conceive how such a book could be dangerous. It appeared to us so grey, so Cimmerian, so corpse-like that we had difficulty in enduring its presence and shuddered before it as before a spectre’. To Goethe, d'Holbach's work seemed to deprive nature and life of all that is precious.”
— Frederick Copleston (2003), The Enlightenment: Voltaire to Kant (pg. 50)

Another translation, by Will Durant (1965), reads as follows: [2]

“Holbach’s System of Nature appeared to us [students at Strasbourg] so dark, so deathlike, that we found it a trouble to endure its presence, and shuddered at it as a specter.”

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Shelley
In 1793, William Godwin, the father of Mary Shelley (wife of Percy Shelley), published Political Justice, which was influenced by the Holbach, Helvetius, and Jean Rousseau, respectively. [3]

In 1806, Percy Shelley, age 16, entered Oxford University, where his favorite amusements were chemistry, microscopic investigations, and boating; before the end of the year, he married Mary Shelley in the “Church of Elective Affinities”, as Mary retrospectively referred to things.

Sometime therein, or shortly thereafter, Shelley read System of Nature, and then began to translate as a means of enlisting the Oxford dons in the campaign against religion; Shelley, supposedly, dates his atheism start from his reading Holbach’s System of Nature. [3]

In 1811, Shelley, age 19, inspired, also, in part, by the proto-atheism work of Benedict Spinoza, wrote, together with Thomas Hogg, a college friend, albeit published anonymously, a 13-page pamphlet “The Necessity of Atheism”, which resulted to be so controversial that it got him expelled from Oxford.

Quotes | Employed
The following are quotes employed in The System of Nature:

“We must expect death with tranquility, seeing that it is only a dissolution of the elements of which each animal is composed.”
Marcus Aurelius (c.175AD), Meditations (Book 2); cited by Baron d’Holbach (1770) in The System of Nature (pg. 130)

“We believe that that which is, will always be, and that the same causes will have the same effects.”
Thomas Hobbes (c.1650), Publication; cited by Baron d’Holbach (1770) in The System of Nature (pg. 124)

Quotes | On
The following are quotes on The System of Nature:

“There was no wit, no shadow, no nuance, no multi-sidedness, no art, no pleasure or erotic play to be found in its pages. It denied god, argued that all religions were created out of fear, ignorance, and anthropism; that souls did not outlive the body; that the world was determined by strict laws.”
Denis Diderot (c.1768), comment to someone on early draft of Holbach’s The System of Nature [4]

“Holbach’s System of Nature is the most able exposition of theological absurdities ever written.”
— Author (c.1771), “Advertisement” to The System of Nature [1]

“Holbach’s System of Nature contains the most comprehensive description of materialism and atheism in the entire history of philosophy.”
Will Durant (1965), The Story of Civilization, Volume 9 The Age of Voltaire [3]

The System of Nature is an incendiary device ticking bomb.”
— Rebecca Scott (2013), Darwin’s Ghosts: in Search of the First Evolutionists [4]

Quotes | By
The following are noted quotes by Holbach in System of Nature:

“We must show them its charms, that we may disgust them with that disgraceful worship, which leads them into errors.”
— Baron d’Holbach (c.1770), title page quote (Ѻ) to 1795 William Hodgson English translation

“The source of man’s unhappiness is his ignorance of nature.”
— Baron d’Holbach (1770), System of Nature (opening preface sentence, pg. viii)

“If man must have chimeras, let him at least learn to permit others to form theirs after their own fashion.”
— Baron d’Holbach (1770), System of Nature (preface, pg. x)

“The beings which he pictures to himself as above nature [see: supernatural], or distinguished from her, are always chimeras formed after that which he has already seen, but of which it is impossible he should ever form any correct idea, either as to the place they occupy, or of their manner of acting.”
— Baron d’Holbach (1770), The System of Nature (pg. 10)

“The distinction which has been so often made between the physical and the moral man is evidently an abuse of terms. Man is a being purely physical: the moral man is nothing more than this physical being considered under a certain point of view, that is to say, with relation to some of his modes of action, arising out of his particular organization.”
— Baron d’Holbach (1770), The System of Nature (pg. 10)

“The enlightened man, is man in his maturity, in his perfection; who is capable of pursuing his own happiness; because he has learned to examine, to think for himself, and not to take that for truth upon the authority of others, which experience has taught him examination will frequently prove erroneous.”
— Baron d’Holbach (1770), The System of Nature (pg. 12)

“The universe, that vast assemblage of every thing that exists, presents only matter and motion : the whole offers to our contemplation nothing but an immense, an uninterrupted succession of causes and effects; some of these causes are known to us, because they strike immediately on our senses; others are unknown to us, because they act upon us by effects, frequently very remote from their original cause.”
— Baron d’Holbach (1770), The System of Nature (pg. 13)

“This truth—that every thing in the universe is in motion; the essence of matter is to act: if we consider its parts attentively, we shall discover that not a particle enjoys absolute repose; those which appear to us to be without motion, are, in fact, only in relative or apparent rest; they experience such an imperceptible motion, and expose it so little on their surfaces, that we cannot perceive the changes they undergo—which is still denied by many metaphysicians, has been conclusively established by the celebrated Toland, in a work which appeared in the beginning of the eighteenth century, entitled Letters to Serena. Those who can procure this scarce work will do well to refer to it, and their doubts on the subject, if they have any, will be removed.”
Denis Diderot (1770), note (pg. 18) to Baron d’Holbach’s §2: Of Motion and its Origin of The System of Nature [6]

“Of those who ask, why does not nature produce new beings, we inquire in turn how they know that she does not do so. What authorizes them to believe this sterility in nature? Do they know whether, in the combinations she is at every instant forming, nature is not occupied in producing new beings without the cognizance of these observers? Who told them whether nature be not now assembling in her vast laboratory the elements fitted to give rise to wholly new generations, that will have nothing in common with the species at present existing. What absurdity, then, would there be in supposing that man, the horse, the fish, the bird, will be no more? Are these animals so indispensable to nature that without them she cannot continue her eternal course? Does not all change around us? Do we not ourselves change? Nature contains no constant forms.”
— Baron Holbach (1770), The System of Nature (pg. 46); variant, supposedly, found in the third edition of Jean Sales’ 1777 The Philosophy of Nature (PI, pgs. 215): “It is reasonable to suppose that nature has: ‘sucked successively every degree of the large scale’ [pacouru successivement tous les degres de la grande echelle]”; cited by Arthur Lovejoy (1933) in The Great Chain of Being (pgs. 269, 366)

“Those who wish to form an idea of the shackles imposed by theology on the genius of philosophers born under the ‘Christian dispensation’, let them read the metaphysical romances of Leibniz, Descartes, Malebranche, Cudworth, etc., and coolly examine the ingenious but rhapsodically systems entitled: the pre-established harmony of occasional causes; physical pre-motion, etc.”
Denis Diderot (1770), note (pgs. 51-52) to Baron d’Holbach’s The System of Nature (1889)

“It is evident that the notion of spirits, imagined by savages and adopted by the ignorant, is calculated to retard the progress of knowledge, since it precludes our researches into the true cause of the effects which we see, by keeping the human mind in apathy and sloth. This state of ignorance may be very useful to crafty theologians, but very injurious to society. This is the reason, however, why in all ages priests have persecuted those who have been the first to give natural explanations of the phenomena of nature— as witness: Anaxagoras, Aristotle, Galileo, Descartes—and, more recently, Richard Carlile, William Lawrence, Robert Taylor, and Abnet Kneeland; to which we may add the name of the learned and venerable Thomas Cooper M. D., lately president of Columbia College. South Carolina.”
H.D. Robinson (1770), notes (pg. 53) to Baron d’Holbach’s The System of Nature (1889)

“What is life, except it be the assemblage of modifications, the congregation of motion, peculiar to an organized being? Life in a body is the totality of its motion; feeling and thought make a part of this motion: thus, in the dead man, these motions will cease like all the others.”
— Baron d’Holbach (1770), The System of Nature (pg. 118)

Laws, as necessary as those which gave him birth, will make him return into the bosom of nature from whence he was drawn, in order to reproduce him afterwards under some new form, which it would be useless for him to know: without consulting him, nature places him for a season in the order of organized beings; without his consent, she will oblige him to quit it to occupy some other order.”
— Baron d’Holbach (1770), The System of Nature (pg. 121)

“Let them speak of immortality to intrepid and noble souls; let them show it as the price of their labors to energetic minds, who, springing forward beyond the boundaries of their actual existence, are little satisfied with eliciting the admiration and with gaining the love of their contemporaries, but are determined also to wrest the homage, to secure the affection of future races. Indeed, there is an immortality to which genius, talents, virtue, have a just right to pretend; do not therefore let them censure or endeavour to stifle so noble a passion in man, which is founded upon his nature, and from which society gathers the most advantageous fruits.”
— Baron d’Holbach (1770), The System of Nature (pg. 133) (see: posthumous genius)

“If the ignorance of nature gave birth to such a variety of gods, the knowledge of this nature is calculated to destroy them.”
— Baron d’Holbach (1770), The System of Nature (pg. 174) (Ѻ); employed by Percy Shelley (1811) in The Necessity of Atheism (pg. #)

Montaigne says ‘Man is not able to be other than he is, nor imagine but after his capacity; let him take what pains he may, he will never have a knowledge of any soul but his own.’ Xenophanes said, ‘If the ox or the elephant understood either sculpture or painting, they would not fail to represent the divinity under their own peculiar figure; that in this, they would have as much reason as Polyclitus or Phidias, who gave him the human form.’ It was said to a very celebrated man that ‘god made man after his own image’; ‘Man has returned the compliment’, replied the philosopher; and L'amotte le Vayer used to remark, that ‘theanthropy (Ѻ) was the foundation of every system of Christianity.
— Baron d’Holbach (1770), The System of Nature (pg. 181)

“Let us banish from the man of genius the chimera which makes him waste his time.”
— Baron d’Holbach (1770), The System of Nature (pg. 298)

“Abandon your chimeras; occupy yourselves with truth; learn the art of happy living; perfect your morals, your governments, and your laws; look to education, to agriculture, and to the sciences that are truly useful; labor with ardor. If you must have chimeras, permit your fellow-creatures to have theirs also; and do not cut the throats of your brethren, when they cannot rave in your own manner. If the infirmities of your nature require an invisible crutch, adopt such as my suit your humor, select those which you may think most calculated to support your tottering frame. Do not let these ‘imaginary beings’ detract from or upset your relations with the ‘real beings’ around you.”
— Baron d’Holbach (1770), System of Nature (pgs. 298-99); note: "chimeras" is a Jean Meslier chapter title; cited by Jennifer Hecht (2003) in Doubt: a History (pgs. 353-54)

“Indeed, what is an atheist? He is a man, who destroys chimeras prejudicial to the human species, in order to reconduct men back to nature, to experience, and to reason. He is a thinker, who, having meditated upon matter, its energy, its properties, and its modes of acting, has no occasion, in order to explain the phenomena of the universe, and the operations of nature, to invent ideal powers, imaginary intelligences, beings of the imagination.”
— Baron d’Holbach (1770), The System of Nature (pg. 300; compare pg. 359)

“It belongs, then, to candor, to disinterestedness, and to reason, to judge whether the natural principles, which have been here brought forward, be destitute of foundation; it is to these upright judges, that a disciple of nature submits his opinions; he has a right to except against the judgment of enthusiasm, of presumptuous ignorance, and interested knavery.”
Baron d’Holbach (1770), The System of Nature (pg. 303); compare Goethe (1814) on Spinoza’s Ethics: “what especially riveted me to him, was the utter disinterestedness, which glowed in his every sentence”

“Indeed, many theologians, in despite of those invectives with which they attempt to overwhelm atheists, appear frequently to have doubted whether any existed in the world, or if there were persons who could honestly deny the existence of a god. Their uncertainty was, with was without doubt, founded upon the absurd ideas which they ascribe to their adversaries, whom they have unceasingly accused of attributing everything to chance, to blind causes, to dead and inert matter, incapable of acting by itself. We have, I think, sufficiently justified the partisans of nature, from these ridiculous accusations; we have, throughout the whole, proved, and we repeat it, that chance is a word devoid of sense, which, as well as the word god, announces nothing but an ignorance of true causes.”
— Baron d’Holbach (1770), The System of Nature (pgs. 303-304); see: Reddit post (Ѻ)

“The gods once destroyed, there remain, in the minds of some atheists, no longer any bonds to connect mortals.”
— Baron d’Holbach (1770), The System of Nature (pg. 310)

“The peaceable Epicurus never disturbed Greece; the poem of Lucretius caused no civil wars in Rome; Bodin was not the author of the league; the writings of Spinoza have not excited the same troubles in Holland, as the disputes of Gomar and d’Arminius. Hobbes did not cause blood to flow in England.”
Baron d’Holbach (1770), The System of Nature (pgs. 311-312)

“What, indeed, is an atheist? He is one who destroys delusions which are harmful to humanity in order to lead men back to nature, to reality, to reason. He is a thinker who, having reflected on the nature of matter, its energy, properties and ways of acting, has no need of idealized powers or imaginary intelligences to explain the phenomena of the universe and the operations of nature.”
— Baron d’Holbach (1770), The System of Nature (pg. 359; compare pg. 300) [5]

References
1. (a) d’Holbach, Baron. (1770). The System of Nature: Laws of the Moral and Physical World (notes by Denis Diderot; translator: H.D. Robinson) (attributed, pgs. iv-v; universally learned, pg. v; translated, pg. v). J.P. Mendum, 1889.
(b) The System of Nature (Translator: H.D. Robinson) – Archive.org.
(c) Holbach, Baron. (1770). d’Holbach, Baron. (1770). The System of Nature: Laws of the Moral and Physical World (notes by Denis Diderot; translator: H.D. Robinson). J.P. Mendum, 1835.
2. Durant, Will. (1965). The Story of Civilization, Volume 10 Rousseau and Revolution: a History of Civilization in France, England, and Germany from 1756, and in the rest of Europe from 1715 to 1789 (pgs. 618-19). Simon & Schuster
3. Durant, Will. (1965). The Story of Civilization, Volume 9 The Age of Voltaire: a History of Civilization in Western Europe from 1715 to 1756, with Special Emphasis on the Conflict between Religion and Philosophy (Durant, pg. 710; Shelley, pg. 713). Simon & Schuster.
4. Scott, Rebecca. (2013). Darwin’s Ghosts: in Search of the First Evolutionists (Voltaire, pg. 157). A&C Black.
5. History of atheism – ArgumentsForAtheism.com.
6. Mahon, Basil (2003). The Man Who Changed Everything – the Life of James Clerk Maxwell (senses, pg. 25). Hoboken, NJ: Wiley.
7. (a) Hort, Fenton J.A. (1882). “Letter to Lewis Campbell”, Feb 4.
(b) Fenton Hort – Wikipedia.
(c) Campbell, Lewis and Garnett, William. (1882). The Life of James Clerk Maxwell: with Selections from His Correspondence and Occasional Writings (pg. 421). MacMillan and Co, 1884.
(d) Anon. (1888). “Review: Natural Causation by C.E. Plumptre”, Journal of Education (pg. 479), Oct 1.
(e) Nørretranders, Tor. (1991). The User Illusion: Cutting Conscious Down to Size (Mærk verden) (pg. v). Publisher: A. Lane, 1998.
(f) Seitz, Frederick. (2001). “James Clerk Maxwell (1831-1879); Member APS 1875” (pdf) (pg. 1; [n. 2, pg. 421]), Proceedings of the American Philosophical Society, 145(1):1-45, Mar.
(g) Flood, Raymond, McCartney, Mark, and Whitaker, Andrew. (2014). James Clerk Maxwell: Perspectives on His Life and Work (pg. 283). Oxford University Press.
8. Roberts, Hugh. (1997). Shelley and the Chaos of History: a New Politics of Religion (pg. 413). Penn State Press, 2010.
9. (a) Holbach, Baron. (1770). The System of Nature: Laws of the Moral and Physical World (translator: Samuel Wilkinson). T. Davison, 1820.
(b) The System of Nature (txt) (Translator: Samuel Wilkinson) – InformationPhilosopher.com.
(c) The System of Nature (Translator: Samuel Wilkinson) – Gutenberg.org.
(d) The System of Nature (Translator: Samuel Wilkinson) – WikiSource.org.

External links
The System of Nature – Wikipedia.

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