ence, between the rays of the Sun, in this respect-some more dense, and some more rare, as in all other bodies. Now, there will be this other difference, arising from this, viz. that the densest rays will come from the Sun, with the most rapid motion; not because they are less obstructed, by the medium they go through, but because, as every body may see, their mutual repercussions in the Sun, before they leap out into the vast cirtumambient expanse, will be much more violent, because of their greater gravity, which we have shown to be the reason of these repercussions. Now, in the first place, we have no reason to think, but that there is a difference in the Density of the Rays of the Sun; and, if so, we are certain, that that will cause a difference in the Rapidity of their Motion; and therefore, certainly would cause a difference in their Refrangibility; for it is certain, that those rays, that move swiftly by a body, will be attracted least by it, and those that move slowest by it, will be attracted most. This will, also, certainly cause a difference in the Reflexibility of Rays; for those rays, that strike on a body with greatest force, will be most dificultly reflected, and those that strike with least force will be reflected most easily those, that strike it most forcibly, are most likely to make their way forward without reflection; and those bodies, that are most likely to stand a stroke of the weaker rays, so as to reflect them, will give way to the stronger rays. Now, whether this difference in the density of the rays be the reason of the different Refrangibility or no; I think we may be sure of this, that, if the true reason were removed, and there should be a difference in the Density of Rays, this would certainly be a new reason of difference in the Refrangibility.

It may be objected to this, that there is an infinite variety in the density of bodies, and so doubtless of rays, and at that rate there would be an infinite variety of simple Colours.-I answer, And so there is; and multitudes have been distinguished, and more might be, if we had instruments and senses sufficiently accurate. The progression, there is from the highest to the lowest colours, is through an infinite variety. But the reason, why there are no colours below Blue, is, because if there are any rays, rarer than the blue, they are so weak, that they degenerate into shade, and are undistinguishable from darkness, and because they have not gravity enough to beget a motion in them, sufficient to cause them to leap out, at such a distance."

This explication.very well agrees with experience. Red is the highest. strongest, harshest colour, because it is caused by the densest and most rapid rays; blue, more gentle and weak. Red gives the most light, because the rays have more of vivacity, and more strongly affect the organ; blue, the nearest approaching to darkness. Red, long beheld, is painful to the eyes; green and blue are pleasing, easy, gentle, inoffensive and healthful to the orgán. Blue is so weak a colour, the rays are so weak, that they are reflected from the weakest bodies, such as air, and their exhalations, as in the blueness of the skies; which are so weak, that they let through the stronger rays; though sometimes at sunsetting, when the air is dense, all the rest of the rays are stopped but the Red, which fight their way through all the exhalations the air is full of, and then the Sun looks as red as blood.

Corollary. Because there is such a difference in the Density of the rays of light, it appears that the Atoms, of which the rays of light are com posed, are immensely less, than the rays themselves.

47. Since, as has been shown, body is nothing but an infinite resistance, in some parts of space, caused by the immediate exercise of Divine power; it follows, that as great and as wonderful power is every moment exerted in the upholding of the world, as at first was exerted in its creation: the first

creation being ouly the first exertion of this power, to cause such resistance, and the preservation, only the continuation or the repetition of this power, every moment to cause this resistance: so that the Universe is created out of nothing every moment. And, if it were not for our imaginations, which hinder us, we might see that wonderful work performed continually, which was seen by the morning stars, when they sang together. 48. There is that, which is peculiarly wonderful in Trees, beyond any thing that is to be found in the inanimate world, even the manner of their growing from the seed. Their amazing diversification into such curious branches, leaves, flowers, fruits, and seeds; and so successively from one seed after another, in the same manner, from age to age, forever.

The discovery of the little tree in the seed, has opened a door for finding out these wonders; but, without that, we might have known that the parts of the tree are in miniature, before they are in perfection; for the bud, which is but another sort of seed, is nothing but the leaves, twigs, flowers and fruits, folded up together, which we see by degrees unfold themselves. But the trees being in embryo in the seed, does not seem to solve the difficulty, for the tree most certainly does not keep to its rule, does not exactly follow its copy in the seed; for we may make the tree grow almost as we please. If we lop the tree, there will peep out new branches from the body of the tree, where there was no sign of a branch. But if the branches of the tree did really grow exactly in the same form as their pattern in the seed, this might indeed solve for the growing of one tree, but not for that infinite succession, and endless offspring, of trees, that may proceed from it; except we suppose that, in one seed, are actually contained an infinite number of trees and seeds, one within another; for this makes actually an infinite number of trees twice over, in the same seed: first, an infinite number of successions of one tree, less than another, and by that time we come to the least, (we must be allowed to speak contradictions here.) the offspring will be so numerous, that there will be actually an infinite number of trees of the same size and standing. Wherefore this matter of the Growth of Trees still remains very difficult.

The reason of it would not be altogether so difficult and perplexing, if they always grew in the same regular order. We do not despair of finding out the reason of that, which always happens alike, and in the same order. Thus, when we have reduced the motion of the Planets to a rule, we have got above half way towards giving the reason of their motions. But the Branches of Trees seem not capable of being reduced to any rule. at all; but there is an infinite variety-one branch grows out here, and another there, without any order.

In

But we shall be helped in this matter, if we consider, that all trees and plants, universally, when they first sprout out of the ground, while there is, as yet, but one twig, are exactly regular; that is, having the buds which grow out of them, which are branches in miniature, standing in a regular and uniform manner-a leaf always growing under the bud. somé, two come out together, one right opposite to the other, always standing transverse to the last two, as in the twig, A B, in the maple tree; In others, but one at a time, standing at regular distances, on different sides, in such order as to stand round the twig, in the form of a screw, so that the branches shall stand out on every side, as in the twig, CD, in the apple, the pear, the cherry, etc.; in others, having two together, growing out of opposite sides, but not standing transverse, like the maples, as in the twig EF In others, having four or five standing round the twig together, as in G; In others, having but one at a time, standing always opposite to each other, as in IK; and innumerable other ways, but yet always regular. And as the first sprouts of the tree are always regular, so are

all the young sprouts of the tree afterwards, when the tree comes to be divided into many branches; yea, always as long as the tree lives, all the twigs, that are of that years growth, are regular. So that it follows, that the body,

the main branches, and the little twigs, and every part, of every tree in the world, in their first beginnings, were regular. So that, if all the trees had continued as they were, in the year that they grew; the whole tree, with all the branches, small and great, would be regular. And now we are sure that, if the sap did not flow, more easily, into one bud or branch than another, or, if one were not otherwise advantaged above another, if all the buds and branches had, in all respects, equal advantages for growing; the tree would be most exactly regular. It follows clearly, and certainly; for, if the common trunk, A B, when it first grew, was regular, and the branches, l, m, n, o, at first were regular, and the branches of the branches, as r s, were also regular, and so on; it is certain, if all these branches continued as they were at first, and every bud or branch expanded itself alike, that the whole tree, A B, will always continue to grow regularly. Thus far we are clear, that the miniatures of all plants are regular, and that there is no provision made, in the seeds and bud, for any but a regular growth, and that, if it were not for some accidental causes that promoted or hindered the growth of one of the branches or buds, no, more than another, that all the tree, in the end, would be regular.

We need not perplex ourselves to find out, what should give one a greater advantage of growth than another. The least thing in the world may be sufficient, when they are so small and tender: ten thousand things might be thought of.

Many plants do actually always continue to grow regular; as most herbs and weeds, that are but of one year's growth, and dome trees; and, of those that err from their seminal pattern, some keep nearer to it than others.

We therefore conclude, that the first trees, that ever were, were regular trees, or at least regular parts of trees, so contrived, with vessels, pipes and valves, that, as it receives more sap, it continually desires to shoot forth towards B. And infinite wisdom so contrived the curious workmanship of the inlets, receptacles, passages and outlets, from A to B, that that which is, by degrees, added at B, by the gentle motion of the sap, from A to B, through the pipes, shall be cast into the same form, and shall come out in the same fashion, as if it were cast into a mould, It is VOL. I.

92

also so contrived, that, as it continues to proceed towards B. the course of some of the passages shall be directed so, as to cause it to shoot forth on the side at n, and at every such regular distance, just as the engineer contrives his clock to strike at uniform distances, and the sap proceeds forwards in the branch, n o, in the same manner as it did in the trunk A B; and in like manner breaks out at the sides, at regular distances from r to s, and then branches forth, in like manner, at the sides of r s, and so on, in infinitum, to the world's end. And the trees, that grow now, are nothing but the branches of those first trees; which, although the communication with the original branch has ceased, yet still continue to grow and to be diversified into more branches, in the same regular and uniform method, in infinitum; and the seeds, from whence our trees proceed, are no new plants, but branches of the old, a continuation of the same plant, in its infinite regular progress-branches not yet expanded. The trees, or seeds, or whatever they were, that God first created, were only the beginning of this progress, enough to set it a going. So it is contrived, that, at such due and uniform distances, these little continuations of the branches of the tree, while they are very tender, shall be wrapped in the curious covering and shelter of leaves, flowers and fruits, and some only of leaves and flowers, and shall drop off; so that when the seed drops off, it is only the regular continuation of these branches. And as it drops into the ground, though the continuation is uninterrupted, yet, receiving sap from the ground, it will not cease to grow: which is no more strange, than that the branch of an apple-tree, if cut off and cast into the ground, will continne to grow.

The leaves are still nothing but branches of the tree, that grow not so big, and so contrived as to cleave together after such a manner. So likewise is the flower, and the fruit too is a compages of branches, yet otherwise modelled. There is nothing belonging to a tree but branches; and all, that the first trees, which God created, had to do, was to proceed to the end of the world, in such regular branches, having various stated periods, at the same stated distances: at which periods, there happen remarkable changes, and unusual phenomena, among the branches, as there may be various periods in an engine of human contrivance: some returning every second, every minute, every quarter of an hour, hour, day, month and year. As for the leaves, flowers and fruits, they are not to be looked upon as a continuation of these regular branches, but as part of the substance of the trunk to which they grow.

There is but here and there one of these buds, that grow thus regularly and expand themselves. Perhaps some die, most of them continue in their littleness and imperfect state; the sap not running plentifully enough into them, having more free passage elsewhere, or being by some means diverted; and so, the part growing bigger, they are at last covered in it, and lie latent, until by some means the passage of the sap elsewhere is stopped, as by lopping of the tree, or otherwise; and then the sap, flowing more plentifully into them, causes them to spring forth, and make their way out of the bark. It may lie, like a seed in the tree, for many years, and, upon such an occasion, spring forth. Hence it is, that those little twigs, how small soever, though but of one year's growth, that grow out of great trees, yet always have their beginning and rise close by the very heart of the tree; because all the rest that is above it has grown and been added, since the tree was so small as to bear buds at that place. We had as good think that trees grow out of the ground, without seeds, as that branches grow out of the trunk without buds; for the buds are but another sort of seeds, that cleave to the tree, and the seeds are but another sort of buds, that drop into the ground.

49. (Vid. 14.) In order to this, it is not only necessary that God should

tell the number of the stars, and know the exact bigness, weight, density, number, and distance, of those great bodies of the Universe; not only that he should weigh the mountains in exact scales, and the hills in perfectly even balances, and measure the seas as in the hollow of his hand; but he must comprehend the dust of the earth in a measure. He must measure the dust of the earth in all these respects-he must know the exact number of the particles of dust, the exact dimensions and weight of every atom, the exact distance of every one, yea, of every part of every one, from every other, yea, from every part of all others in the universe. Thus, Infinite Wisdom is as much concerned, not only in the excellent Arrangement of the world, but in the simple Creation of it, as Infinite Power. Yea, one single atom cannot have a being without it one single atom could not move without it, inasmuch as we have shown, that motion cannot be without Infinite Wisdom; and again, that no body could have being, without motion, any otherwise, than as the world had a being from all eternity.

50. The only way that the soul can influence the body is by the emitting of animal spirits from the brain; and when the soul retracts animal spirits from some part, it is by emission in others. This emission is either natural, which follows merely from the presence of the soul in the brain; or voluntary, that which follows of itself, from thoughts and passions. And the only way that the body has influence upon the soul, is by the influx of animal spirits to the brain, or efflux from it.

51. When I come to speak of the Body of Man, lét a demonstration of the Soul, being distinct from matter, be inserted.

52. (Vid. 17.) That is, the least wrong step, would thus disorder all things, and quite overthrow the Universe, except God, from time to time, set the whole Universe a going anew; which would be necessary, because the least wrong turn in one atom causes a wrong motion in every atom in the Universe; and this also, returning at the end of some given period, or continuing at intervals of time, longer or shorter, equal or unequal, would at length overthrow the Universe.

53. I believe all Fluidity arises from Repulsion.

54. If the Fixed Stars moved round the Earth in twenty-four hours, none of them would be seen here upon the earth; none of their rays would ever reach the Earth: For although it cannot be demonstrated how far distant they are from us, yet they must needs be so far distant, that such a motion would be at least ten times so swift as the motion of the rays of light. According to the ordinary computation of their distance, it would be several thousand times swifter. But we will suppose it to be ten times. Where

fore, I say, that if E

the motion of the Star at S, round

the Earth T, be ten times so swift as the motion of the bodies emitted on all sides, from the body S, none of those emitted bodies will ever reach the body T. In such cases, it is evident, that bodies So emitted, would have a twofold motion; viz. a motion whereby they are emitted

W