them without any assistance from outward objects. The first is evident of itself, and the second will appear so too, if we consider that in learning their names, and the signification of these names, we learned to decompound them; and that by learning to decompound some, the mind was instructed to compound others, even such, perhaps, as existed by these means in idea and notion, before the combinations, whereof they became the archetypes, existed in act. Our ideas of relations, and of the relations of relations which are comprehended so often in our complex ideas, or notions, are not positive beings that exist by themselves, and can be contemplated by themselves. Modes are the affections and dependences of substances; relations are the affections and dependences of substances and modes; and no one of them can exist any longer than both the ideas that produced it, or by the comparison of which it was framed, subsist. It might seem therefore the less likely, that outward objects should communicate such ideas to the mind, or even instruct the mind to frame them; yet so it is. That act of the mind that sets two objects before our internal sight, and by referring from one to the other includes both in the same consideration, is plainly suggested to us by the operations of outward objects on our senses. We can neither look up nor down, without perceiving ideas of bigger and less, of more and fewer, of brighter and darker, and a multitude of other relations, the ideas of which arise in the mind as fast as the ideas of things of which they express the relations, and almost prevent reflection. When the mind, thus taught, employs reflection, the number of these relative ideas increases vastly. Thus, for instance, when we observe the alterations that are made by nature, or by art, in our complex ideas of substances, or when we reflect on the continual vicissitude and flux of all the affections and passions, and the consequences of them, how can we avoid framing the ideas of cause and effect? That which produces, or seems to us to produce the alteration gives us the idea of cause, and that which receives the alteration gives us the idea of effect. I go no further into the consideration of our ideas of relations physical, and moral. They are numberless, and they must needs be so; since every idea, or notion we have, though it be in itself one single object of thought, becomes the object of a thousand when it is compared with all those with which it may be compared in some respect or other.

SECTION III.

THESE, and such as these are all the ideas we have really, and are capable of having, derived originally from sense, external

and internal. These too, and such as these are the faculties by which we improve and increase our stock, and such as all these are, such must our knowledge be; for since human knowledge is nothing else that the perception of the agreement or disagreement, connection or repugnancy of our ideas, those that are simple must determine the nature of those that are complex; those that are complex that of our notions; our notions that of the principles we establish, and that of the principles we establish that of all the consequences we draw from them. Error, in any one step of this gradation, begets error in all that follow: and though we compare ever so exactly, conclude ever so truly, and in a word reason ever so well, our reasoning must terminate in error whenever this happens. It cannot terminate in knowledge. But before I leave this subject, I must go over it again, that I may carry the reflections upon it further.

How inadequate our ideas are to the nature of outward objects, and how imperfect, therefore, all our knowledge is concerning them, has been observed transiently above, and has been too often and too well explained to be over much insisted on by me. That there are such objects, material objects, neither spirits nor ideas, and that they act in one another and on us in various manners, and according to various laws, no man can doubt, any more than he can doubt of that perception by which he distinguishes their presence and their absence, according to the difference between the ideas they excite in one case, and those he retains in the other. We can doubt of this, I think, no more than we can doubt whether we are free agents, or whether we are necessarily determined to all we do; no more than we can doubt of many other things of which philosophers have pretended to doubt, or have really doubted: for either, they have meant on many occasions to exercise their wit, and to triumph in the subtilty of their genius, or they have been transported by overheated imaginations into a philosophical delirium. The first have perplexed knowledge more than they have improved it: and if the last have not made many converts, whilst they have argued against self-evidence, they have multiplied useless disputes, and misspent much time.

Here, then, at our first setting out in the survey of knowledge, we find an immense field in which we cannot range, no, nor so much as enter beyond the outskirts of it: the rest is impenetrable to us, and affords not a single path to conduct us forward. Could we range in that field, we should be unable to walk in our own. I mean, that if our senses were able to discover to us the inmost constitutions, and the real essences of outward objects, such senses would render us unfit to live, and act in the system to which we belong. If the system was not made for us, who

pretend on very weak grounds, I think, to be the final cause of it, we at least were made for the system, and for the part we bear, among terrestrial animals. Other creatures there may be, and I believe readily there are, who have finer senses than men, as well as superior intelligence to apply and improve the ideas they receive by sensation. The inmost constitutions, the real essences of all the bodies that surround them, may lie constantly open to such creatures; or they may be able, which is a greater advantage still, so "to frame, and shape to themselves organs of sensation, as to suit them to their present design, and the circumstances of the object they would consider," according to that supposition which Mr. Locke calls an extravagant conjecture of his, but which that great man might very reasonably make; since it assumes no more than this, that some other creatures are able to do by their natural constitution, and so as to obtain full and absolute knowledge, what we are able to do by art very imperfectly, and yet so as to attain a greater degree of partial and relative knowledge than our senses, unassisted by art, could communicate to us.

But be this as it will, concerning which we can only guess; it is, I think, evident, that although outward objects make impressions on the organs of sense, and may be said therefore to cause sensations, yet these sensations are determined in the whole animal kind that we know, and to which we belong, according to the constitutions of the several species, as these constitutions are framed according to the uses and ends for which each species is designed, and to which it is directed. Innumerable instances might be brought to illustrate, and confirm this truth. It will be sufficient to do so by making a few short observations on our own species alone. The same outward objects then produce the same sensations in all men, as far as self-preservation is immediately concerned: and there is at least an apparent uniformity of sensations in all other cases, sufficient to maintain the commerce of men one with another, to direct their mutual offices without confusion, and to answer all the ends of society. Further than to these purposes, the determination of their sensations does not seem to be in all men the same. The same objects seem to cause different, and opposite sensations in many particular instances, in as much as they give pleasure, and excite desire in one man, whilst they give no pleasure, nor excite any desire, nay whilst they give pain, and provoke aversion in another. All men feel alike the effects of fire that burns, or of steel that divides their flesh: and my butler, who has tasted both, will not bring me a bottle of wormwood-wine when I ask for a bottle of sack. But yet the Greenlander quaffs his bowl of whale's-grease with as much pleasure as you and I drink our

bowl of punch: and if his liquor appears nauseous to us, ours appears so to him. Habit, that second nature, may sometimes account, as well as sickness, for this difference that seems to be in human sensations. But still it will remain true, that this difference, in many and various instances, proceeds from our first nature, if I may say so; that is, from a difference in the original constitution of those particular bodies in which this apparent difference of sensation is perceivable. The principle of this diversity is as unknown to us as the more general principle of uniformity; but whether it be laid in the natural constitution, or in the alterations that habit or sickness may produce, our observation will be verified, that human sensations are determined by the actual disposition, whether original or accidental, of human bodies, and cannot therefore help to communicate to us any knowledge of the inward constitutions, or real essences of the bodies which excite them, nor indeed any knowledge but of themselves. To discover in what manner, and by what powers, external action and internal passion co-operate to produce sensation, it is in vain to attempt: and a philosophical mind will be much better employed in admiring and adoring the divine wisdom that appears equally in the diversity, and in the uniformity of our sensations, as it would not be hard to show if this was a place for those reflections, than in such vain researches. Vain indeed they will appear to be to any man of sense, who considers with attention and without prepossession, what has been written on this subject by men of the greatest genius.

But as vain as these researches are, and as impossible as it is to know more of our sensations than that we have them, and that we receive them from outward objects, yet are we not to think the use of our senses as limited, as Malebranche would have us believe it to be. They were given,* he says, for the preservation of our bodies, and not to teach us truth. The first part of this assertion is agreeable to the system of nature. The latter is agreeable, I think, to no system but that of his own imagining, which is so extravagantly hypothetical in many, and the principal parts, that it has made no great fortune in the world, though the utmost subtilty of wit, and all the powers of language are employed to support it. Notwithstanding, therefore, such systems as these, for it is not single of its kind, we may continue to believe what constant experience dictates to us, that our senses, though few, confined, and fallible, are given not only for the preservation of our bodies, but to let into the human mind the first elements of knowledge, and to assist, and direct the mind in all the progress it makes afterwards.

* Recherche de la Veritè, 1. 1, c. 10.

That human knowledge is relative, not absolute, has been said already. We neither do, nor can know the real essence of any one substance in the world, not of our own: and when we talk of the powers, and qualities, and sometimes of the natures of substances, either we talk ignorantly, or we refer to their effects, by which alone we distinguish them, and in which alone we know any thing of them. They who distinguish between the primary, and secondary qualities of substances, do not so much. as pretend that the secondary qualities, such as colors, or tastes for instance, are any representations of the outward existences that cause them: and the disputes about solidity, extension, and motion which is mobility in action, as mobility is motion in power, show how inadequate our ideas are of the primary qualities; though these are said to be resemblances of patterns really existing in all bodies whether we perceive them or not.

But though the knowledge here spoken of be not complete, nor absolute, because our ideas, concerning which alone human knowledge is conversant, are inadequate to the nature of things; yet is it real knowledge in some degree, and relatively to us. This I mean. Our simple ideas, whose various co-existences compose all our complex ideas of substances, are certainly adequate in this sense; they are real effects of real powers, and such as the all-wise Author of nature has ordained these powers to produce in us. I say in us, for it is not incongruous to suppose, nor will these ideas be less adequate, nor this knowledge less real, if it be so that the same powers may be ordained to produce other effects on other creatures of God. This paper gives me the idea that I call white; it may give some other idea to some other creature. These ideas are different, but they are both adequate to our use, and the knowledge real; for they are both real, and natural effects of real, corresponding powers.

As low as these principles, of any real knowledge that we can acquire of substances, are laid, it is from them we must take our rise: and there is no wonder therefore if we proceed slowly, and have not been able to proceed far even since the study of nature has been pursued in a right method. Whilst the symbolical physics of Pythagoreans and Platonists prevailed, and whilst natural philosophy was made to consist in little else than a logical cant, which Aristotle invented, and his disciples propagated, error was cultivated instead of science, ignorance was masked, and men passed for naturalists without any knowledge of nature. The case would be much the same if some modern philosophers could have succeeded in establishing a supposed science that they call metaphysics, to be like a higher ground from which we might descend to physics, from generals to particulars, from speculations about what may be, down to affirmations about what is. But