ciples we establish that of all the consequences we draw from them. Errour, in any one step of this gradation, begets errour 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 errour 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 imperfcct, 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 on 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 meaned, on many occa sions, to exercise their wit, and to triumph in

the

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, while they have argued against self evidence, they have multiplied useless disputes, and mispent 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 them"selves organs of sensation, as to suit them to

"their

"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 confu

But

sion, 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, while they give no pleasure, nor excite any desire, nay, while 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. 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

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 cooperate 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 writ 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 * Recherche de la Verité, L. 1, c. 10.

of