no reason why the rays of light variously reflected to our eyes, should excite in us the sensations of various colours, nor why the motion of the air should excite the idea of sound, or the fire heat, or sugar sweetness, or the like. By experience we know that it is so, but why or how it is so, of this we know nothing. This we must resolve into the will of the Creator, Who has so ordered, and Who doubtless might have ordered otherwise had He so pleased.

Seventhly, Besides the sensations which external bodies excite in our mind, by our organs of sense, as the immediate objects of these organs, we also find from experience, that they produce many other sensible effects, both upon our bodies and upon each other, when applied to action. Thus ipecacuan, besides the ideas of its colour, taste, and smell, which it excites in our mind by the organs of our senses, when taken into the stomach, also produces sickness; opium allays pain, and causes sleep; wine intoxicates; and so of other things. These effects of different bodies we know by experience; but we are totally ignorant why they produce them, or what particular quality or disposition it is in each, which produces the effect proper to it. But as experience teaches us that they constantly do produce these effects, in the same circumstances, we naturally attribute to each body a quality, power, or virtue proper to itself, bestowed upon it by the Creator; and all such powers of bodies may be included under the general name of sensible qualities, because they manifest themselves to our senses by the effects which they produce.

Eighthly, If we inquire in what all these sensible qualities of bodies consist, or what is that particular disposition of each body, by which it produces the effects proper to it, we must acknowledge our total ignorance,

and confess that we know nothing. If we suppose the original matter, which composes the substance of bodies, to be the same in all, and that it acts mechanically, which seems to be the most generally received opinion, then we can conceive no other way of accounting for the different qualities of different bodies, than by the figure, motion, and combination of the particles of matter in the structure of each.

It is true, indeed, that a difference in these things alters the sensible qualities of bodies; witness the various and opposite qualities of quicksilver, according to the various changes wrought in the structure of its component parts by fire; and it seems to be the approved opinion of philosophers, that all the vast variety of productions from the earth is owing only to the dif ferent modifications of the same nutritive juice, according to the different plants by which it is imbibed. But whether this be really the case, and holds good in all varieties of creatures—or if there be, in fact, different kinds of primitive matter, of which bodies are composed, and to which their various qualities are owing, we know not. Whether these qualities of bodies arise from the mechanical structure of their parts; or if they be the immediate effect of the divine will, impressed upon different compositions of the same original matter, by way of a law, we are entirely ignorant.

Phil. What you have said seems perfectly clear, and the substance of it may, I think, be thus summed up in a few words: the sensible effects which various bodies produce, either in ourselves, or in each other, are objects of knowledge, of which we are absolutely certain, from the testimony of our senses. From these sensible effects we justly argue the existence of the bodies which produce them; and we also infer that those bodies have in

themselves certain qualities by which they are capable of producing these effects. But with regard to the matter or substance of the bodies in which those qualities reside, its nature and structure, or the nature of the qualities themselves by which the effects are produced, this is entirely hidden from our eyes. All this I easily understand, as it is extremely clear; but I do not perceive what connection it has with transubstantiation.

Orth. That we shall now see, after taking a view of our manner of reasoning concerning the substance of bodies. Let us suppose, then, according to the general opinion of the learned, that the elementary matter, or materia prima, of all bodies, is the same throughout the whole creation; and that the vast diversity of material objects arises only from different forms in their composition and structure. This original matter is the common substance of all bodies; its particular structure in various bodies constitutes their essential diversity, or their different natures; and it is by their sensible qualities, as perceived by us, that we distinguish one substance from another. Hence, for instance, what we properly understand by the substance of iron, is the elementary matter formed in such a manner as to excite in our minds that collection of sensible qualities which we perceive in iron. What we understand by the substance of bread, is a portion of the same elementary matter, so formed as to excite in our mind that other collection of sensible qualities which we perceive in bread; and so of all others.

Now it is reasonable to suppose that the Author of Nature acts uniformly in the ordinary course of nature, and that when effects are the same, the causes also producing them are the same. When, therefore, we find the same collection of sensible qualities in different bodies,

we conclude that their substance is the same; and, on the contrary, when we find the sensible qualities in one body different from those in another, we conclude that their substances are different, although, in reality, we know nothing whatever of the nature of the one substance or of the other, nor in what their difference consists. Thus, in examining a piece of iron and a piece of wood, we find the collection of sensible qualities in the one very different from those in the other; and therefore we distinguish them as different substances, and give them different names. But when we examine two pieces of iron, or two pieces of wood, by themselves, we find the sensible qualities of both the same; and therefore we conclude that their substance also is the same, and we apply to them the same name.

The sensible qualities of bodies are the immediate and sole objects of our senses, and with regard to them our senses are the sole and absolute judges, from whose ultimate sentence there is no appeal. In like manner, whatever changes occur in these qualities fall immediately under the cognisance of the particular senses, to which it belongs to give us proper and certain information of such changes. From such information we argue that if any change be produced in the qualities, there must also be a corresponding change in the nature of the body itself, by which these effects are produced, although we are ignorant wherein this change in the cause consists. But where our senses inform us of no change in the qualities, we conclude that there is no change in the body from which these effects proceed.

Now, though this manner of reasoning be most just, and may be safely depended upon in all the ordinary occurrences of life, at least where we have no positive reason to doubt it; yet we see no impossibility in sup

posing that Almighty God may cause two very different substances so to act upon us as to affect our senses in the very same way, and thereby exhibit to us the same sensible qualities. Nay, we are so far from seeing any impossibility in this, that we know from revelation it has often been the case.

The substance of a human being, composed of a soul and body, is confessedly very different from that of an angel, which is purely spiritual; and yet it is certain, from the Word of God, that angels have often assumed the sensible qualities of living men,-that is, have appeared as such to the sight of those who beheld them— have spoken and conversed in their hearing-have taken hold of them, and wrestled with them-have walked, sat down, ate, drank, and exhibited themselves to the senses of those who beheld them, in the same way that a man would.

It cannot be called in question that there is an infinite distance between the bodily substance of a dove, composed of flesh and blood, and the incomprehensible substance of the Divinity; and yet we know that, when our blessed Saviour was baptised in the Jordan, the Holy Ghost, the third Person of the adorable Trinity, was pleased to exhibit Himself to those present, under the outward appearance of a dove, affecting their sight in the same way that a dove would have done, had it been hovering over our Saviour at the time. In these and other similar cases related in Scripture, it is plain that the above way of arguing, from the sameness of the sensible effects, to the sameness or similarity of the cause producing them, would not hold. This may be farther illustrated even in natural things; for how often do we see cooks, apothecaries, and vintners, compounding dishes, drugs, and various wines, representing so exactly