under their confideration, than they will probably have in the time to come. Yet he who makes these sciences the study of his life, may perhaps collect particulars concerning their evidence, which, though known to a few, are unknown to many; may fet fome principles in a more striking light than that in which they have been formerly viewed; may devise methods of confuting new errors, and expofing new paradoxes; and may hit upon a more popular way of difplaying what has hitherto been exhibited in too dark and myfterious a form.

It is commonly allowed, that the fcience of human nature is of all human fciences the most curious and important. To know ourfelves, is a precept which the wife in all ages. have recommended, and which is enjoined by the authority of revelation itself.

Can

any thing be of more confequence to man, than to know what is his duty, and how he may arrive at happiness? It is from the examination of his own heart, that he receives the first intimations of the one, and the only fure criterion of the other.-What can be more ufeful, more delightful, and more fublime, than to contemplate the Deity? It is in the works of nature, particularly in the conftitution of the human foul, that we difcern the first and most confpicuous traces of the Almighty; for without fome previous acquaintance with our own moral nature, we could not have any certain knowledge of His. -Deftitute

-Destitute of the hope of immortality, and a future retribution, how contemptible, how miferable is man! And yet, did not our moral feelings, in concert with what reason difcovers of the Deity, evidence the probability of a future state, and that it is necessary to the full vindication of the divine government, we should be much less qualified, than we now are, to judge rationally of that revelation, by which life and immortality have been brought to light.

How then is this fcience to be learned ? In what manner are we to study human nature? Doubtless by examining our own hearts and feelings, and by attending to the conduct of other men. But are not the writings of philofophers ufeful towards the attainment of this fcience? Moft certainly they are for whatever improves the fagacity of judgement, the fenfibility of moral perception, or the delicacy of tafte; whatever renders our knowledge of moral and intellectual facts more extenfive; whatever impreffes our minds with more enlarged and more powerful fentiments of duty, with more affecting views of God and Providence, and with greater energy of belief in the doctrines of natural religion;-every thing of this fort either makes us more thoroughly acquainted, or prepares us for becoming more thoroughly acquainted with our own nature, and with that of other beings, and with the relations they and we bear to one another. But I fear

we

we shall not be able to improve ourselves in any one of these refpects, by reading the modern fyftems of fcepticifm. What account then are we to make of those systems and their authors? The following effay is partly defigned as an anfwer to this question. But it has a further view: which is, to examine the foundations of this fcepticism, and fee whether these be consistent with what all mankind acknowledge to be the foundations of truth; to inquire, whether the cultivation of fcepticism be falutary or pernicious to science and mankind; and whether it may not be poffible to devife certain criteria, by which the abfurdity of its conclufions may be detected, even by thofe who may not have leifure, or fubtlety, or metaphyfical knowledge, fufficient to qualify them for a logical confutation of all its premifes. If it be confeffed, that the present age has fome tendency to licentiousness, both in principle and practice, and that the works of fceptical writers have fome tendency to favour that licentiousness; it will also be confeffed, that this defign is neither abfurd nor unfeafonable.

*

A celebrated writer on human nature has obferved, that "if truth be at all within the "reach of human capacity, it is certain it

must lie very deep and abstruse:" and a little after he adds, "that he would esteem "it a ftrong prefumption against the philo¬

* Treatife of Human Nature, vol. 1. p. 3. 4.

fophy

fophy he is going to unfold, were it so very eafy and obvious." I am fo far from adopting this opinion, that I declare, in regard to the few things I have to fay on human nature, that I fhould efteem it a very strong prefumption against them, if they were not easy and obvious. Physical and mathematical truths are often abftrufe; but facts and experiments relating to the human mind, when expreffed in proper words, ought to be obvious to all. I find that thofe poets, hiftorians, and novelifts, who have given the most lively difplays of human nature, and who abound most in sentiments eafily comprehended, and readily admitted as true, are the most entertaining, as well as the most useful. How then fhould the philofophy of the human mind be fo difficult? Indeed, if it be an author's determinate purpose to advance paradoxes, fome of which are incredible, and others beyond comprehenfion; if he be willing to avail himself all he can of the natural ambiguity of language in fupporting those paradoxes; or if he enter upon inquiries too refined for human understanding; he must often be obfcure, and often unintelligible. But my views are very different. I intend only to fuggeft fome hints for guarding the mind against error; and these, I hope, will be found to be deduced from principles which every man of common capacity may examine by his daily experience.

It is true, that several subjects of intricate fpeculation

I

fpeculation are treated of in this book. But I have endeavoured, by conftant appeals to fact and experience, by illuftrations and examples the most familiar I could think of, and by a plainnefs and perfpicuity of expreffion which fometimes may appear too much affected, to treat of them in a way, that I hope cannot fail to render them intelligible, even to those who are not much converfant in ftudies of this kind. Truth, like virtue, to be loved, needs only to be feen. My principles require no difguife; on the contrary, they will, if I mistake not, be most easily admitted by those who beft understand them. And I am perfuaded, that the fceptical fyftem would never have made fuch an alarming progrefs, if it had been well understood. The ambiguity of its language, and the intricacy and length of fome of its fundamental investigations, have unhappily been too fuccessful in producing that confufion of thought, and indiftinctnefs of apprehenfion, in the minds both of authors and readers, which are fo favourable to error and fophistry.

Few men have ever engaged in controverfy, religious, political, or philofophical, without being in fome degree chargeable with mifconception of the adverfary's meaning. That I have never erred in this way, I dare not affirm. But I am confcious of having done every thing in my power to guard against it. The greater part of these papers VOL. I.

C

have