truth and it would be well if we would not, but would ingenuously own the shortness of our sight where we do not see. To say there can be no other, because we conceive no other, does not, I confess, much instruct. And if I should say, that it is possible God has made our souls so, and so united them to our bodies, that, upon certain motions made in our bodies by external objects, the soul should have such or such perceptions or ideas, though in a way inconceivable to us; this perhaps would appear as true and as instructive a proposition as what is so positively laid down.

9. Though the peripatetic doctrine* of the species does not at all satisfy me, yet I think it were not hard to show, that it is as easy to account for the difficulties he charges on it, as for those his own hypothesis is laden with. But it being not my business to defend what I do not understand, nor to prefer the learned gibberish of the schools, to what is yet unintelligible to me in P. M. I shall only take notice of so much of his objections, as concerns what I guess to be the truth. Though I do not think any material species, carrying the resemblance of things by a continual flux from the body we perceive, bring the perception of them to our senses; yet I think the perception we have of bodies at a distance from ours, may be accounted for, as far as we are capable of understanding it, by the motion of particles of matter coming from them and striking on our organs. In feeling and tasting there is immediate contact. Sound is not unintelligibly explained by a vibrating motion communicated to the medium; and the effluvia of odorous bodies will, without any great diffi culties, account for smells. And therefore P. M. makes his objections only against visible species, as the most difficult to be explained by material causes, as indeed they are. But he that shall allow extreme smallness in the particles of light, and exceeding swiftness in their motion; and the great porosity that must be granted in bodies, if we compare gold, which wants them not, with air, the medium wherein the rays of light come

*Recherche de la Vérité, 1. 3. pt. 2. c. 2.

to our eyes, and that of a million of rays that rebound from any visible area of any body, perhaps the ro or To part coming to the eye, are enough to move the retina sufficiently to cause a sensation in the mind; will not find any great difficulty in the objections which are brought from the impenetrability of matter, and these rays ruffling and breaking one another in the medium which is full of them. As to what is said, that from one point we can see a great number of objects, that is no objection against the species, or visible appearances of bodies, being brought into the eye by the rays of light; for the bottom of the eye or retina, which, in regard of these rays, is the place of vision, is far from being a point. Nor is it true, that though the eye be in any one place, yet that the sight is performed in one point, i.e. that the rays that bring those visible species do all meet in a point; for they cause their distinct sensations, by striking on distinct parts of the retina, as is plain in optics; and the figure they paint there must be of some considerable bigness, since it takes up on the retina an area whose diameter is at least thirty seconds of a circle, whereof the circumference is in the retina, and the centre somewhere in the crystalline; as a little skill in optics will manifest to any one that considers, that few eyes can perceive an object less than thirty minutes of a circle, whereof the eye is the centre. And he that will but reflect on that seeming odd experiment of seeing only the two outward ones of three bits of paper stuck up against a wall, at about half a foot, or a foot one from another, without seeing the middle one at all, whilst his eye remains fixed in the same posture, must confess that vision is not made in a point, when it is plain, that looking with one eye there is always one part between the extremes of the area that we see, which is not seen at the same time that we perceive the extremes of it; though the looking with two eyes, or the quick turning of the axis of the eye to the part we would distinctly view, when we look but with one, does not let us take notice of it.

10. What I have here said I think sufficient to make

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intelligible, how by material rays of light visible species may be brought into the eye, notwithstanding any of P. M.'s objections against so much of material causes as my hypothesis is concerned in. But when by this means an image is made on the retina, how we see it, I conceive no more than when I am told we see it in God. How we see it, is, I confess, what I understand not in the one or in the other, only it appears to me more difficult to conceive a distinct visible image in the uniform invariable essence of God, than in variously modifiable matter; but the manner how I see either, still escapes my comprehension. Impressions made on the retina by rays of light, I think I understand; and motions from thence continued to the brain may be conceived, and that these produce ideas in our minds, I am persuaded, but in a manner to me incomprehensible. This I can resolve only into the good pleasure of God, whose ways are past finding out. And, I think, I know it as well when I am told these are ideas that the motion of the animal spirits, by a law established by God, produces in me; as when I am told they are ideas I see in God. The ideas it is certain I have, and God both ways is the original cause of my having them; but the manner how I come by them, how it is that I perceive, I confess I understand not; though it be plain motion has to do in the producing of them and motion, so modified, is appointed to be the cause of our having them; as appears by the curious and artificial structure of the eye, accommodated to all the rules of refraction and dioptrics, that so visible objects might be exactly and regularly painted on the bottom of the eye.

11. The change of bigness in the ideas of visible objects, by distance and optic-glasses, which is the next argument he uses against visible species, is a good argument against them, as supposed by the peripatetics; but when considered, would persuade one that we see the figures and magnitudes of things rather in the bottom of our eyes than in God: the idea we have of them and their grandeur being still proportioned to the bigness of the area, on the bottom of our eyes, that is

affected by the rays which paint the image there; and we may be said to see the picture in the retina, as, when it is pricked, we are truly said to feel the pain in our finger.

12. In the next place where he says, that when we look on a cube "we see all its sides equal." This, I think, is a mistake; and I have in another place shown, how the idea we have from a regular solid, is not the true idea of that solid, but such an one as by custom (as the name of it does) serves to excite our judgment to form such an one.

13. What he says of seeing an object several millions of leagues, the very same instant that it is uncovered, I think may be shown to be a mistake in matter of fact. For by observations made on the satellites of Jupiter, it is discovered that light is successively propagated, and is about ten minutes coming from the sun to us.

14. By what I have said, I think it may be understood how we may conceive, that from remote objects material causes may reach our senses, and therein produce several motions that may be the causes of ideas in us; notwithstanding what P. M. has said in this second chapter against material species. I confess his arguments are good against those species as usually understood by the peripatetics: but, since my principles have been said to be conformable to the Aristotelian philosophy, I have endeavoured to remove the difficulties it is charged with, as far as my opinion is concerned in them.

15. His third chapter is to confute the "opinion of those who think our minds have a power to produce the ideas of things on which they would think, and that they are excited to produce them by the impressions which objects make on the body." One who thinks ideas are nothing but perceptions of the mind annexed to certain motions of the body by the will of God, who hath ordered such perceptions always to accompany such motions, though we know not how they are produced; does in effect conceive those ideas or perceptions to be only passions of the mind, when produced in it, whether we will or no, by external objects. But he conceives them to be a mixture of action

says,

and passion when the mind attends to them, or revives them in the memory. Whether the soul has such a power as this, we shall perhaps have occasion to consider hereafter; and this power our author does not deny, since in this very chapter he "When we conceive a square by pure understanding, we can yet imagine it; i. e. perceive it in ourselves by tracing an image of it on the brain." Here then he allows the soul power to trace images on the brain, and perceive them. This, to me, is matter of new perplexity in his hypothesis; for if the soul be so united to the brain as to trace images on it, and perceive them, I do not see how this consists with what he says a little before in the first chapter, viz. " that certainly material things cannot be united to our souls after a manner necessary to its perceiving them."

16. That which is said about objects exciting ideas in us by motion; and our reviving the ideas we have once got in our memories, does not, I confess, fully explain the manner how it is done. In this I frankly avow my ignorance, and should be glad to find in him any thing that would clear it to me; but in his explications I find these difficulties which I cannot get over.

17. The mind cannot produce ideas, says he, because they are "real spiritual beings," . e. substances; for so is the conclusion of that paragraph, where he mentions it as an absurdity to think they are "annihilated when they are not present to the mind." And the whole force of this argument would persuade one to understand him so; though I do not remember that he any where speaks it out, or in direct terms calls them substances.

18. I shall here only take notice how inconceivable it is to me, that a spiritual, i. e. an unextended substance, should represent to the mind an extended figure, v. g. a triangle of unequal sides, or two triangles of different magnitudes. Next, supposing I could conceive an unextended substance to represent a figure, or be the idea of a figure, the difficulty still remains to conceive how it is my soul sees it. Let this substantial being be ever so sure, and the picture ever so clear; yet how we