been so lucky in solving an infinite number of phenomena of nature? This surely would be a greater prodigy than philosophy ever exhibited. Add to this, that upon the contrary hypothesis, to wit, that the objects of sight are internal, no account can be given of any one of those appearances, nor any physical cause assigned why a visible object should, in any one case, have one apparent figure and magnitude rather than another.

Thus I have considered every argument I have found advanced to prove the existence of ideas, or images of external things, in the mind: and if no better arguments can be found, I cannot help thinking, that the whole history of philosophy has never furnished an instance of an opinion so unanimously entertained by philosophers upon so slight grounds.

A third reflection I would make upon this subject is, That philosophers, notwithstanding their unanimity as to the existence of ideas, hardly agree in any one thing else concerning them. If ideas be not a mere fiction, they must be, of all objects of human knowledge, the things we have best access to know, and to be acquainted with; yet there is nothing about which men differ so much.

Some have held them to be self-existent, others to be in the Divine Mind, others in our own minds, and others in the brain or sensorium: I considered the hypothesis of images in the brain, in the fourth chapter of this essay. As to images in the mind, if any thing more is meant by the image of an object in the mind than the thought of that object, I know not what it means. The distinct conception of an object may, in a metaphorical or analogical sense, be called an image of it in the mind. But this image is only the conception of the object, and not the object conceived. It is an act of the mind, and not the object of that act.

Some philosophers will have our ideas, or a part of them, to be innate; others will have them all to be adventitious: some derive them from the senses alone; others from sensation and reflection: some think they are fabricated by the mind itself; others that they are produced by external objects; others that they are the immediate operation of the Deity; others say, that impressions are the causes of ideas, and that the causes of impressions are unknown: some think that we have ideas only of material objects, but none of minds, of their operations, or of the relations of things; others will have the immediate object of every thought to be an idea: some think we have abstract ideas, and that by this chiefly we are distinguished from the brutes; others maintain an abstract idea to be an absurdity, and that there can be no such thing: with some they are the immediate objects of thought, with others the only objects.

A fourth reflection is, That ideas do not make any of the operations of the mind to be better understood, although it was probably with that view that they have been first invented, and afterwards so generally received.

We are at a loss to know how we perceive distant objects; how we remember things past; how we imagine things that have no existence. Ideas in the mind seem to account for all these operations: they are all, by the means of ideas, reduced to one operation; to a kind of feeling, or immediate perception of things present, and in contact with the percipient; and feeling is an operation so familiar, that we think it needs no explication, but may serve to explain other operations.

But this feeling, or immediate perception, is as difficult to be comprehended, as the things which we pretend to explain by it. Two things may be in contact without any feeling or perception; there must therefore be in the percipient a power to feel or to perceive. How this power is

produced, and how it operates, is quite beyond the reach of our knowledge. As little can we know whether this power must be limited to things present, and in contact with us. Nor can any man pretend to prove, that the Being, who gave us the power to perceive things present, may not give us the power to perceive things that are distant, to remember things past, and to conceive things that never existed.

Some philosophers have endeavoured to make all our senses to be only different modifications of touch; a theory which serves only to confound things that are different, and to perplex and darken things that are clear. The theory of ideas resembles this, by reducing all the operations of the human understanding to the perception of ideas in our own minds. This power of perceiving ideas is as inexplicable as any of the powers explained by it: and the contiguity of the object contributes nothing at all to make it better understood; because there appears no connexion between contiguity and perception, but what is grounded on prejudices, drawn from some imagined similitude between mind and body; and from the supposition, that, in perception, the object acts upon the mind, or the mind upon the object. We have seen how this theory has led philosophers to confound those operations of mind which experience teaches all men to be different, and teaches them to distinguish in common language; and that it has led them to invent a language inconsistent with the principles upon which all language is grounded.

The last reflection I shall make upon this theory is, That the natural and necessary consequences of it furnish a just prejudice against it to every man who pays a due regard to the common sense of mankind.

Not to mention, that it led the Pythagoreans and Plato to imagine that we see only the shadows of external things, and not the things themselves, and that it gave rise to the Peripatetic doctrine of sensible species, one of the greatest absurdities of that ancient system, let us only consider the fruits it has produced, since it was new-modelled by Des Cartes. That great reformer in philosophy saw the absurdity of the doctrine of ideas coming from external objects, and refuted it effectually, after it had been received by philosophers for thousands of years; but he still retained ideas in the brain and in the mind. Upon this foundation, all our modern systems of the powers of the mind are built. And the tottering state of those fabrics, though built by skilful hands, may give a strong suspicion of the unsoundness of the foundation.

It was this theory of ideas that led Des Cartes, and those that followed him, to think it necessary to prove, by philosophical arguments, the existence of material objects. And who does not see that philosophy must make a very ridiculous figure in the eyes of sensible men, while it is employed in mustering up metaphysical arguments, to prove that there is a sun and a moon, an earth and a sea? Yet we find these truly great men, Des Cartes, Malebranche, Arnauld, and Locke, seriously employing them selves in this argument.

Surely their principles led them to think, that all men, from the beginning of the world, believed the existence of these things upon insufficient grounds, and to think that they would be able to place upon a more rational foundation this universal belief of mankind. But the misfortune is, that all the laboured arguments they have advanced, to prove the existence of those things we see and feel, are mere sophisms: not one of them will bear examination.

I might mention several paradoxes, which Mr. Locke, though by no means fond of paradoxes, was led into by this theory of ideas. Such as,

that the secondary qualities of body are no qualities of body at all, but sensations of the mind: That the primary qualities of body are resemblances of our sensations: That we have no notion of duration, but from the succession of ideas in our minds: That personal identity consists in consciousness; so that the same individual thinking being may make two or three different persons, and several different thinking beings make one person: That judgment is nothing but a perception of the agreement or disagreement of our ideas. Most of these paradoxes I shall have occasion to examine.

However, all these consequences of the doctrine of ideas were tolerable, compared with those which came afterwards to be discovered by Berkeley and Hume: That there is no material world: No abstract ideas or notions: That the mind is only a train of related impressions and ideas, without any subject on which they may be impressed: That there is neither space nor time, body nor mind, but impressions and ideas only: And, to sum up all, That there is no probability, even in demonstration itself, nor any one proposition more probable than its contrary.

These are the noble fruits which have grown upon this theory of ideas, since it began to be cultivated by skilful hands. It is no wonder that sensible men should be disgusted at philosophy, when such wild and shocking paradoxes pass under its name. However, as these paradoxes have, with great acuteness and ingenuity, been deduced by just reasoning from the theory of ideas, they must at last bring this advantage, that positions so shocking to the common sense of mankind, and so contrary to the decisions of all our intellectual powers, will open men's eyes, and break the force of the prejudice which hath held them entangled in that theory.

CHAPTER XV.

ACCOUNT OF THE SYSTEM OF LEIBNITZ.

THERE is yet another system concerning perception, of which I shall give some account, because of the fame of its author. It is the invention of the famous German philosopher Leibnitz, who, while he lived, held the first rank among the Germans in all parts of philosophy, as well as in mathematics, in jurisprudence, in the knowledge of antiquities, and in every branch, both of science and of literature. He was highly respected by emperors, and by many kings and princes, who bestowed upon him singular marks of their esteem. He was a particular favourite of our Queen Caroline, consort of George II., with whom he continued his correspondence by letters after she came to the Crown of Britain, till his death.

The famous controversy between him and the British mathematicians, whether he or Sir Isaac Newton was the inventor of that noble improvement in mathematics, called by Newton the method of fluxions, and by Leibnitz the differential method, engaged the attention of the mathematicians in Europe for several years. He had likewise a controversy with the learned and judicious Dr. Samuel Clarke, about several points of Newtonian philosophy which he disapproved. The papers which gave occasion to this controversy, with all the replies and rejoinders, had the honour to be transmitted from the one party to the other through the hands of Queen Caroline, and were afterwards published.

His authority, in all matters of philosophy, is still so great in most parts of Germany, that they are considered as bold spirits, and a kind of heretics,

who dissent from him in any thing. Wolfius, the most voluminous writer in philosophy of this age, is considered as the great interpreter and advocate of the Leibnitzian system, and reveres as an oracle whatever has dropped from the pen of Leibnitz. This author proposed two great works upon the mind. The first, which I have seen, he published with the title of Psychologia empirica, seu experimentalis. The other was to have the title of Psychologia rationalis; and to it he refers for his explication of the theory of Leibnitz with regard to the mind. But whether it was published I have not learned.

I must therefore take the short account I am to give of this system from the writings of Leibnitz himself, without the light which his interpreter Wolfius may have thrown upon

it.

Leibnitz conceived the whole universe, bodies as well as minds, to be made up of monads, that is, simple substances, each of which is, by the Creator in the beginning of its existence, endowed with certain active and perceptive powers. A monad, therefore, is an active substance, simple, without parts or figure, which has within itself the power to produce all the changes it undergoes from the beginning of its existence to eternity. The changes which the monad undergoes, of what kind soever, though they may seem to us the effect of causes operating from without, yet they are only the gradual and successive evolutions of its own internal powers, which would have produced all the same changes and motions, although there had been no other being in the universe.

Every human soul is a monad joined to an organised body, which organised body consists of an infinite number of monads, each having some degree of active and of perceptive power in itself. But the whole machine of the body has a relation to that monad which we call the soul, which is, as it were, the centre of the whole.

As the universe is completely filled with monads, without any chasm or void, and thereby every body acts upon every other body, according to its vicinity or distance, and is mutually re-acted upon by every other body, it follows, says Leibnitz, that every monad is a kind of living mirror, which reflects the whole universe, according to its point of view, and represents the whole more or less distinctly.

I cannot undertake to reconcile this part of the system with what was before mentioned, to wit, that every change in a monad is the evolution of its own original powers, and would have happened though no other substance had been created. But to proceed.

The

There are different orders of monads, some higher, and others lower. The higher orders he calls dominant; such is the human soul. monads that compose the organised bodies of men, animals, and plants, are of a lower order, and subservient to the dominant monads. But every monad, of whatever order, is a complete substance in itself, indivisible, having no parts, indestructible, because, having no parts, it cannot perish by any kind of decomposition: it can only perish by annihilation, and we have no reason to believe that God will ever annihilate any of the beings which he has made.

The monads of a lower order may, by a regular evolution of their powers, rise to a higher order. They may successively be joined to organised bodies, of various forms and different degrees of perception; but they never die, nor cease to be in some degree active and percipient.

This philosopher makes a distinction between perception and what he calls apperception. The first is common to all monads, the last proper to the higher orders, among which are human souls.

By apperception he understands that degree of perception which reflects, as it were, upon itself; by which we are conscious of our own existence, and conscious of our perceptions; by which we can reflect upon the operations of our own minds, and can comprehend abstract truths. The mind, in many operations, he thinks, particularly in sleep, and in many actions common to us with the brutes, has not this apperception, although it is still filled with a multitude of obscure and indistinct perceptions, of which we are not conscious.

He conceives that our bodies and minds are united in such a manner, that neither has any physical influence upon the other. Each performs all its operations by its own internal springs and powers; yet the operations of one correspond exactly with those of the other, by a pre-established harmony; just as one clock may be so adjusted as to keep time with another, although each has its own moving power, and neither receives any part of its motion from the other.

So that according to this system all our perceptions of external objects would be the same, though external things had never existed; our perception of them would continue, although, by the power of God, they should this moment be annihilated: we do not perceive external things because they exist, but because the soul was originally so constituted, as to produce in itself all its successive changes, and all its successive perceptions, independently of the external objects.

Every perception or apperception, every operation, in a word, of the soul, is a necessary consequence of the state of it immediately preceding that operation; and this state is the necessary consequence of the state preceding it; and so backwards, until you come to its first formation and constitution, which produces successively, and by necessary consequence, all its successive states to the end of its existence: so that in this respect the soul, and every monad, may be compared to a watch wound up, which having the spring of its motion in itself, by the gradual evolution of its own spring, produces all the successive motions we observe in it.

In this account of Leibnitz's system concerning monads, and the preestablished harmony, I have kept as nearly as I could to his own expressions, in his New System of the nature and communication of substances, and of the union of soul and body; and in the several illustrations of that new system which he afterwards published; and in his Principles of nature and grace founded in reason. I shall now make a few remarks upon this system.

1. To pass over the irresistible necessity of all human actions, which makes a part of this system, that will be considered in another place, I observe first, that the distinction made between perception and apperception is obscure and unphilosophical. As far as we can discover, every operation of our mind is attended with consciousness, and particularly that which we call the perception of external objects; and to speak of a perception of which we are not conscious, is to speak without any meaning.

As consciousness is the only power by which we discern the operations of our own minds, or can form any notion of them, an operation of mind of which we are not conscious, is, we know not what; and to call such an operation by the name of perception, is an abuse of language. No man can perceive an object, without being conscious that he perceives it. No man can think, without being conscious that he thinks. What men are not conscious of, cannot therefore, without impropriety, be called either perception or thought of any kind. And if we will suppose operations of mind, of which we are not conscious, and give a name to such creatures of our imagination, that name must signify what we know nothing about.