where we fee like fenfible qualities, that they have like fecret powers, and lay our account, that effects, fimilar to thofe, which we have experienced, will follow from them. If a body of like colour and confiftence with that bread, which we have formerly eat, be presented to us, we make no fcruple of repeating the experiment, and expect, with certainty, like nourishment and fupport. Now this is a process of the mind or thought, of which I would willingly know the foundation. 'Tis allowed on all hands, that there is no known connection between the fenfible qualities and the fecret powers; and confequently, that the mind is not led to form fuch a conclufion concerning their conftant and regular conjunction, by any thing which it knows of their nature. As to paft Experience, it can be allowed to give direct and certain information only of thofe precife objects, and that precife period of time, which fell under its cognizance: But why this experience should be extended to future times, and to other objects, which, for aught we know, may be only in appearance fimilar; this is the main question on which I would infift. The bread, which I formerly eat, nourished me; that is, a body of fuch fenfible qualities, was, at that time, endued with fuch fecret powers: But does it follow, that other bread must also nourish me at another time, and that like fenfible qualities must always be attended with like fecret powers? The confequence feems no

way neceffary. At least, it must be acknowleged, that there is here a confequence drawn by the mind; that there is a certain step taken; a process of thought, and an inference, which wants to be explained. These two propofitions are far from being the fame, I have found that fuch an object has always been attended with fuch an effect, and I forefee, that other objects, which are, to appearance, fimilar, will be attended with fimilar effects. I fhall allow, if you please, that the one propofition may juftly be inferred from the other: I know in fact, that it always is inferred. But if you infift, that the inference is made by a chain of reasoning, I defire you to produce that reafoning. The connection between these propofitions is not intuitive. There is required a medium, which may enable the mind to draw fuch an inference, if indeed it be drawn by reasoning and argument. What that medium is, I must confefs, paffes my comprehenfion; and 'tis incumbent on thofe to produce it, who affert, that it really exifts, and is the origin of all our conclufions concerning matter of fact.

THIS negative argument must certainly, in process of time, become altogether convincing, if many penetrating and able philofophers fhall turn their inquiries this way; and no one be ever able to difcover any connecting propofition or intermediate ftep, which fupports the understanding in this conclufion. But as the question is yet new, every reader may not truft fo

far

far to his own penetration, as to conclude, because an argument efcapes his research and enquiry, that there fore it does not really exist. For this reason it may be requifite to venture upon a more difficult task ; and enumerating all the branches of human knowlege, endeavour to fhew, that none of them can afford fuch an argument.

ALL reafonings may be divided into two kinds, viz. demonftrative reasonings, or those concerning relations of ideas, and moral reasonings or those concerning matter of fact and existence. That there are no demonstrative arguments in the cafe, feems evident; fince it implies no contradiction, that the course of nature may change, and that an object seemingly like those which we have experienced, may be attended with different or contrary effects. May I not clearly and distinctly conceive, that a body falling from the clouds, and which, in all other refpects, resembles fnow, has yet the tafte of falt or feeling of fire? Is there any more intelligible propofition than to affirm, that all the trees will flourish in DɛCEMBER and JANUARY, and decay in MAY and JUNE? Now whatever is intelligible, and can be dif tinctly conceived, implies no contradiction, and can never be proved falfe by any demonftrative arguments or abstract reasonings à priori.

If we be, therefore, engaged by arguments to put trust in past experience, and make it the ftandard of our future judgment, these arguments must be probable only, or fuch as regard matter of fact and real existence, according to the divifion above-mentioned. But that there are no arguments of this kind, must appcar, if our explication of that fpecies of reafoning be admitted as folid and fatisfactory. We have faid, that all arguments concerning existence are founded on the relation of cause and effect; that our knowlege of that relation is derived entirely from experience, and that all our experimental conclufions proceed upon the fuppofition that the future will be conformable to the paft. To endeavour, therefore, the proof of this laft fuppofition by probable arguments, or arguments regarding existence, must be evidently going in a circle, and taking that for granted, which is the very point in queftion.

In reality, all arguments from experience are founded on the fimilarity, which we difcover among natural objects, and by which we are induced to expect effects fimilar to thofe, which we have found to follow from fuch objects. And tho' none but a fool or madman will ever pretend to difpute the authority of experience, or to reject that great guide of human life; it may furely be allowed a philosopher to have fo much curiofity at leaft, as to examine the principle of human nature which gives this mighty authority to experience,

experience, and makes us draw advantage from that fimilarity, which nature has placed among different objects. From causes, which appear fimilar, we expet fimilar effects. This is the fum of all our experimental conclufions. Now it seems evident, that if this conclufion were formed by reafon, it would be as perfect at first, and upon one instance, as after ever fo long a course of experience. But the cafe is far otherwise. Nothing fo like as eggs; yet no one, on account of this apparent fimilarity, expects the fame taste and relish in all of them. "Tis only after a long course of uniform experiments in any kind, that we attain a firm reliance and fecurity with regard to a particular event. Now where is that procefs of reafoning, which from one inftance draws a conclufion, fo different from that which it infers from an hundred inftances, that are no way different from that fingle inftance? This question I propose as much for the fake of information, as with an intention of raifing difficulties. I cannot find, I cannot imagine any fuch reasoning. But I keep my mind still open to inftruction, if any one will vouchfafe to beftow it

on me.

SHOULD it be faid, that from a number of uniform experiments, we infer a connection between the fenfible qualities and the fecret powers; this, I muft confefs, feems the fame difficulty, couched in diffe

rent