The fundamental principle of the atheism of Spinoza is the doctrine of the simplicity of the universe, and the unity of that substance, in which he supposes both thought and matter to inhere. There is only one substance, says he, in the world; and that substance is perfectly simple and indivisible, and exists every where, without any local presence. Whatever we discover externally by sensation; whatever we feel internally by reflection; all these are nothing but modifications of that one, simple, and necessarily existent being, and are not possest of any separate or distinct existence. Every passion of the soul; every configuration of matter, however different and various, inhere in the same substance, and preserve in themselves their characters of distinction, without communicating them to that subject, in which they inhere. The same substratum, if I may so speak, supports the most different modifications, without any difference in itself; and varies them, without any variation.

Neither time, nor place, nor all the diversity of nature are able to produce any composition or change in its perfect simplicity and identity.

I believe this brief exposition of the principles of that famous atheist will be sufficient for the present purpose, and that without entering farther into these gloomy and obscure regions, I shall be able to shew, that this hideous hypothesis is almost the same with that of the immateriality of the soul, which has become so popular. To make this evident, let us[10] remember, that as every idea is derived from a preceding perception, it is impossible our idea of a perception, and that of an object or external existence can ever represent what are specifically different from each other. Whatever difference we may suppose betwixt them, it is still incomprehensible to us; and we are obliged either to conceive an external object merely as a relation without a relative, or to make it the very same with a perception or impression.

[10] Part II, Sect. 6.

The consequence I shall draw from this may, at first sight, appear a mere sophism; but upon the least examination will be found solid and satisfactory. I say then, that since we may suppose, but never can conceive a specific deference betwixt an object and impression; any conclusion we form concerning the connexion and repugnance of impressions, will not be known certainly to be applicable to objects; but that on the other hand, whatever conclusions of this kind we form concerning objects, will most certainly be applicable to impressions. The reason is not difficult. As an object is supposed to be different from an impression, we cannot be sure, that the circumstance, upon which we found our reasoning, is common to both, supposing we form the reasoning upon the impression. It is still possible, that the object may differ from it in that particular.

But when we first form our reasoning concerning the object, it is beyond doubt, that the same reasoning must extend to the impression: And that because the quality of the object, upon which the argument is founded, must at least be conceived by the mind; and could not be conceived, unless it were common to an impression; since we have no idea but what is derived from that origin. Thus we may establish it as a certain maxim, that we can never, by any principle, but by an irregular kind[11] of reasoning from experience, discover a connexion or repugnance betwixt objects, which extends not to impressions; though the inverse proposition may not be equally true, that all the discoverable relations of impressions are common to objects.

[11] Such as that of Sect. 2, form the coherence of our perceptions.

To apply this to the present case; there are two different systems of being presented, to which I suppose myself under necessity of assigning some substance, or ground of inhesion. I observe first the universe of objects or of body: The sun, moon and stars; the earth, seas, plants, animals, men, ships, houses, and other productions either of art or nature. Here Spinoza appears, and tells me, that these are only modifications; and that the subject, in which they inhere, is simple, incompounded, and indivisible. After this I consider the other system of beings, viz. the universe of thought, or my impressions and ideas.

There I observe another sun, moon and stars; an earth, and seas, covered and inhabited by plants and animals; towns, houses, mountains, rivers; and in short every thing I can discover or conceive in the first system. Upon my enquiring concerning these, Theologians present themselves, and tell me, that these also are modifications, and modifications of one simple, uncompounded, and indivisible substance. Immediately upon which I am deafened with the noise of a hundred voices, that treat the first hypothesis with detestation and scorn, and the second with applause and veneration. I turn my attention to these hypotheses to see what may be the reason of so great a partiality; and find that they have the same fault of being unintelligible, and that as far as we can understand them, they are so much alike, that it is impossible to discover any absurdity in one, which is not common to both of them. We have no idea of any quality in an object, which does not agree to, and may not represent a quality in an impression; and that because all our ideas are derived from our impressions.

We can never, therefore, find any repugnance betwixt an extended object as a modification, and a simple uncompounded essence, as its substance, unless that repugnance takes place equally betwixt the perception or impression of that extended object, and the same uncompounded essence. Every idea of a quality in an object passes through an impression; and therefore every perceivable relation, whether of connexion or repugnance, must be common both to objects and impressions.

But though this argument, considered in general, seems evident beyond all doubt and contradiction, yet to make it more clear and sensible, let us survey it in detail; and see whether all the absurdities, which have been found in the system of Spinoza, may not likewise be discovered in that of Theologians.[12]

[12] See Bayle's dictionary, article of Spinoza.

First, It has been said against Spinoza, according to the scholastic way of talking, rather than thinking, that a mode, not being any distinct or separate existence, must be the very same with its substance, and consequently the extension of the universe, must be in a manner identifyed with that, simple, uncompounded essence, in which the universe is supposed to inhere. But this, it may be pretended, is utterly impossible and inconceivable unless the indivisible substance expand itself, so as to correspond to the extension, or the extension contract itself, so as to answer to the indivisible substance. This argument seems just, as far as we can understand it; and it is plain nothing is required, but a change in the terms, to apply the same argument to our extended perceptions, and the simple essence of the soul; the ideas of objects and perceptions being in every respect the same, only attended with the supposition of a difference, that is unknown and incomprehensible.

Secondly, It has been said, that we have no idea of substance, which is not applicable to matter; nor any idea of a distinct substance, which is not applicable to every distinct portion of matter. Matter, therefore, is not a mode but a substance, and each part of matter is not a distinct mode, but a distinct substance. I have already proved, that we have no perfect idea of substance; but that taking it for something, that can exist by itself, it is evident every perception is a substance, and every distinct part of a perception a distinct substance: And consequently the one hypothesis labours under the same difficulties in this respect with the other.

Thirdly, It has been objected to the system of one simple substance in the universe, that this substance being the support or substratum of every thing, must at the very same instant be modifyed into forms, which are contrary and incompatible. The round and square figures are incompatible in the same substance at the same time. How then is it possible, that the same substance can at once be modifyed into that square table, and into this round one? I ask the same question concerning the impressions of these tables; and find that the answer is no more satisfactory in one case than in the other.

It appears, then, that to whatever side we turn, the same difficulties follow us, and that we cannot advance one step towards the establishing the simplicity and immateriality o the soul, without preparing the way for a dangerous and irrecoverable atheism. It is the same case, if instead o calling thought a modification of the soul, we should give it the more antient, and yet more modish name of an action. By an action we mean much the same thing, as what is commonly called an abstract mode; that is, something, which, properly speaking, is neither distinguishable, nor separable from its substance, and is only conceived by a distinction of reason, or an abstraction. But nothing is gained by this change of the term of modification, for that of action; nor do we free ourselves from one single difficulty by its means; as will appear from the two following reflexions.

First, I observe, that the word, action, according to this explication of it, can never justly be applied to any perception, as derived from a mind or thinking substance. Our perceptions are all really different, and separable, and distinguishable from each other, and from everything else, which we can imagine: and therefore it is impossible to conceive, how they can be the action or abstract mode of any substance. The instance of motion, which is commonly made use of to shew after what manner perception depends, as an action, upon its substance, rather confounds than instructs us. Motion to all appearance induces no real nor essential change on the body, but only varies its relation to other objects. But betwixt a person in the morning walking a garden with company, agreeable to him; and a person in the afternoon inclosed in a dungeon, and full of terror, despair, and resentment, there seems to be a radical difference, and of quite another kind, than what is produced on a body by the change of its situation.

As we conclude from the distinction and separability of their ideas, that external objects have a separate existence from each other; so when we make these ideas themselves our objects, we must draw the same conclusion concerning them, according to the precedent reasoning. At least it must be confest, that having idea of the substance of the soul, it is impossible for us to tell how it can admit of such differences, and even contrarieties of perception without any fundamental change; and consequently can never tell in what sense perceptions are actions of that substance. The use, therefore, of the word, action, unaccompanyed with any meaning, instead of that of modification, makes no addition to our knowledge, nor is of any advantage to the doctrine of the immateriality of the soul.