propofition of Euclid fo fimple as not to confift of more parts, than are to be found in any moral reafoning, which runs not into chimera and conceit. Where we trace the principles of the human mind thro' a few keps, we may be very well fatisfy'd with our progrefs; if we confider how foon nature throws a bar to all our enquiries concerning causes, and reduces us to an acknowlegement of our ignorance. The chief obftacle, therefore, to our improvement in the moral or metaphyfical fciences is the obfcurity of the ideas, and ambiguity of the terms. The principal difficulty in the mathematics is the length of inferences and compass of thought, requifite to the forming any conclufion. And perhaps, our progress in natural philosophy is chiefly retarded by the want of proper experiments and phænomena, which often are difcover'd by chance, and cannot always be found, when requifite, even by the most diligent and prudent enquiry. As moral philofophy feems hitherto to have received lefs improvements than either geometry or phyfics, we may conclude, that, if there be any difference in this re. fpect among these fciences, the difficulties, which obstruct the progrefs of the former, require fuperior care and capacity to be furmounted.

THERE are no ideas, which occur in metaphyfics, more obfcure and uncertain, than thofe of power, „force, energy, or necessary connexion, of which it is every

moment necefiay for us to treat in all our disquifi

We, therefore, endeavour, in this effay, to fix, if poffible, the precife meaning of these terms, and thereby remore some part of that obscurity, which is to much complain`d of in this fpecies of philosophy.

It seems a propofition, which will not admit of much difpute, that all our ideas are nothing but copics of our impremions, or in other words, that 'tis impoffible for us to think of any thing, which we have not antecedently felt, either by our external or internal fenfes. I have endeavour'd in a former ef. fay to explain and prove this propofition, and have exprefs'd my hopes, that, by a proper application of it, men may reach a greater clearness and precifion in philofophical reafonings, than what they have hitherto been ever able to attain. Complex ideas may, perhaps, be well known by definition, which is nothing but an enumeration of those parts or fimple ideas, that compofe them. But when we have pufh'd up definitions to the moft fimple ideas, and find ftill fome ambiguity and obfcurity; what refource are we then poffefs'd of? By what invention can we throw light upon these ideas, and render them altogether precife and determinate to our intellectual

* Essay II.

lectual view? Produce the impreffions or original sentiments, from which the ideas are copy'd. These impressions are all strong and fenfible. They admit not of ambiguity and obfcurity. They are not only plac'd in a full light themselves, but may throw light on their correfpondent ideas, which lie in obfcurity. And by this means, we may, perhaps, attain a new microscope or species of optics, by which, in the moral sciences, the most minute and moft fimple ideas may be fo enlarg'd as to fall readily under our apprehenfion, and be equally known with the groffeft and moft fenfible ideas, which can be the object of our enquiry.

To be fully acquainted, therefore, with the idea of power or neceffary connexion, let us examine its im preffion; and in order to find the impreffion with greater certainty, let us fearch for it in all the fources, from which it may poffibly be deriv'd.

WHEN We look about us towards external objects, and confider the operation of causes, we are never able, in a fingle inftance, to difcover any power or neceffary connexion; any quality, which binds the effect to the caufe, and renders the one an infallible confequence of the other. We only find, that the one does actually, in fact, follow the other. The impulfe of one billiard-ball is attended with motion

824
488

E 3.

in.

in the fecond. This is the whole, that appears to the outward fenfes. The mind feels no fentiment or inaward impreffion from this fucceffion of objects: Confequently, there is not in any fingle, particular inftance of cause and effect, any thing which can fuggeft the idea of power or neceffary connexion..

FROM the first appearance of an object, we never can conjecture what effect will refult from it. But were the power or energy of any caufe discoverable by the mind, we could foresee the effect, even without experience, and might, at first, pronounce with certainty concerning it, by the mere dint of thought and reasoning.

In reality, there is no part of matter, that does ever, by its fenfible qualities, difcover any power or energy, or give us ground to imagine, that it could produce any thing, or be follow'd by any other object, which we could denominate its effect. Solidity, extenfion, motion; thefe qualities are all compleat in themselves, and never point out any other event, which may refult from them The scenes of the universe are continually shifting, and one object follows another in an uninterrupted fucceffion; but the power or force, which actuates the whole machine, is entirely conceal'd from us, and never discovers itself in any of the fenfible qualities of body. We know,

that

that, in fact, heat is a conftant attendant of flame; but what is the connexion betwixt them, we have no room fo much as to conjecture or imagine. "Tis impoffible, therefore, that the idea of power can be deriv'd from the contemplation of bodies, in fingle inftances of their operation; because no bodies ever difcover any power, which can be the original of this idea *.

1

SINCE, therefore, external objects, as they appear to the fenfes, give us no idea of power or necessary connexion, by their operations in particular inftances; let us see, whether this idea be deriv`d from reflection on the operations of our own minds, and be copy'd from any internal impreffion. It may be faid, that we are every moment conscious of power in our own minds, while we feel, that, by the fimple command of our will, we can move the organs of our body, or direct the faculties of our minds, in their operation. An act of volition produces motion in our limbs, or raises a new idea in our imagination. This influence of the will we know by consciousness. E 4 Hence

* Mr. Locke, in his chapter of power, fays, that finding from experience, that there are feveral new productions in matter, and concluding that there must fomewhere be a power, capable of producing them, we arrive at last by this reasoning at the idea of power. But no reasoning can ever give us a new, original, fimple idea; as this philofopher himself confeffes. This, therefore, can never be the ori ginal of that idea.