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there for the denying and refuting of a vacuum, and drawing out and enlarging these in such a manner as that the ens may appear to keep that contiguity by being placed in a certain light necessity; but that if they were very much agitated they would admit a vacuum; as in

sources of acting forms only and influences, for that matter is not simply but altogether destitute of active influence. And these assertions flow from an incredible error, unless the miracle be removed by its having been an inveterate and general opinion. For there is scarcely any error similar than that a person should not deem the active in-water hourglasses, in which if there be rather a fluence that virtue infused into matter, (through which it is kept from decay, so that the very least portion of matter is not buried in the whole bulk of the world, nor destroyed by the power of all the active influences, or in any way annihilated, and can be reduced to order; nay, can occupy a portion of space and preserve resistance with impenetrable dimension, and itself by turns be capable of some action, and not forsake itself.) When, on the contrary, it is by far the most potent of all influences, and evidently insuperable, and, as it were, a mere fate and necessity. Yet this virtue Telesius does not attempt to refer to heat or cold. And rightly so: for neither do fire or numbness and congelation add or detract any thing from it nor have any power over it, when it yet meanwhile flourishes in the sun, at the centre of the earth, and everywhere. But he seems to fail, in that he recognises a certain and defined bulk of matter, is blind to that influence which should defend itself and preserve itself in its several parts, and (as it were, be clouded in the darkest shades of the Peripatetics) puts that in the place of an accessory, when it is mainly the principal, poising its own body, removing another, solid and adamantine in itself, and whence emanate by an inviolable authority the decrees of the possible and the impossible. In the same manner the vulgar school puerilely catches at it with an easy grasp of words, imagining that the judgment is satisfied by making a canon of the impossibility of two bodies occupying the same space, but does not take into actual and full consideration that influence and the measure of which we speak; overlooking how much depends upon it, and how great a light would thence be thrown upon science. But to our point, that influence, whatever is its nature, is not comprehended in the elements of Telesius. We must now pass to that influence itself, which is, as it were, the antistrophe to this former, that namely which preserves the connexion of matter. For as matter will not suffer itself to be overwhelmed and perish by matter, so neither can it be separated from matter. And yet it is very doubtful whether this law of nature is equally peremptory with that other.

But Telesius like Democritus supposed a vacuum heaped together and unbounded, that each ens singly might lay down its contiguous ens, and sometimes desert it involuntarily and with difficulty, (as they say,) but with a greater and a subdued violence, and he endeavoured to demonstrate this by sundry experiments, adducing especially those things which are cited here and

small aperture through which the water can descend, they will want a spiracle for the water to descend; but if a larger foramen even without a spiracle, the water being incumbent with a greater bulk on the foramen, and in no way impeding the vacuum above, is carried downwards. So in bellows, in which if you compress and shut them so that there be left no place for the air to glide in, and you afterward elevate and expand them, if the skin of the bellows be slight and weak, it will break, not so if very thick and firm; and other experiments in like manner. But these experiments are neither exactly proved, nor are they quite satisfactory, nor conclusive on the question, and though Telesius thinks he adds to discoveries by means of them, and endeavours after a more subtle discernment of what others have seen but confusedly, yet he does not come off equal to his subject, nor educe a true conclusion, but fails in the means: the misfortune, indeed, of Telesius and the Peripatetics, who in looking into experiments are like owls, not through the inefficiency of their faculties, but through the cataracts of opinions and impatience of fixed and full contemplation. But the very difficult question how far a vacuum is to be admitted, and with respect to what spaces there can be a coition or separation of seeds, and what there is on this head that is peremptory and invariable, I leave to my dissertation on the vacuum. Nor does it relate much to my present purpose whether nature utterly abhors a vacuum, or (as Telesius imagines himself to speak more accurately) entities delight in mutual contact. This we hold to be plain that whether it be avoidance of a vacuum or inclination to contact does not in any degree depend on heat and cold, nor does Telesius assert that it doth, nor can it be so ascribed from any appearance in the things themselves: since matter moved from its place attracts doubtless other matter, whether that be hot or cold, liquid or dry, hard or soft, friendly or adverse, so that a warm would sooner attract the coldest body to come to it, than suffer itself to be disjoined from and deserted by every kind of body. For the bond of matter is stronger than the aversion of heat and cold: and the sequacity of matter has no respec to the diversity of special forms; and so this influence of connexion is by no means from thos elements of heat and cold. The two influence that are mutually opposite follow, which confe red (as may be seen) this rule of elements up a heat and cold, but by a right badly explicated. I mean those influences through which entities

matter is laid on the space than is in proportion to the heat or cold. But these assertions, though not absolutely absurd, seem, nevertheless, like the imaginations of men unwilling to go from their first opinions, and who do not follow reality and nature. For if heat and cold be added to bodies thus extended or compressed, and that in a greater degree accords with the body itself, as, if the stretched cloth be warmed at the fire, it will not in any way make up for the thing, or extin

open and rarefy themselves, dilate and expand so as to occupy a greater space, and dispose themselves into a more extensive orbit; or, other hand, shut up and condense themselves, so as to retire from the space they occupied and betake themselves to a narrower sphere. We must show, therefore, how far that influence hath its rise in heat and cold, and how far it dwells apart, and has a separate nature from that other influence. And that is certainly true, which Telesius affirms, that rarity and density are, as it were, the pecu-guish the impetus of recovery. We have, then, liar works of heat and cold; for the most essential requisite, in respect of these, is that the bodies should occupy a greater and a less space; but yet these dogmas are received rather confusedly: for bodies seem sometimes to migrate from one natural site to another, and to transfer themselves, and that freely and, as it were, willingly, and changing their forms; but sometimes they seem only driven from their natural site, and to return to their accustomed site, their old form remaining the same. And that progressive influence entering on a new site is commonly determined by heat and cold but that other restorative influence is not so. For water expands itself into vapour and air, oil likewise, and fat substances, into steam and flame, by the power of heat, and, if they have completely transmigrated, do not return. Nay, even the air itself is dilated and extended by heat. But if the migration shall have been half full after the departure of heat, it easily falls back into itself; so as that there are also some properties of heat and cold in the restorative influence itself. But those which, without any intervening heat or violence, are extended and divided, even without any addition of cold or subtraction of heat, most readily are returned to their former sites when the force ceases, as in the blowing of a glass egg, and in the emptying of bellows. But that is far more evident in solid and dense bodies. For if cloth, or a string of an instrument be stretched, when the force is taken away, they leap back with great swiftness, and the same is the nature of compression. For the air, drawn together and confined with some violence, breaks forth with a considerable effort, and so the whole of that mechanical motion by which a hard is struck by a hard body, which is commonly called the motion of force, through which solid bodies are discharged, and fly through the air or water, is nothing else than the contending of the parts of the discharged body to free themselves from compression. And yet here are no traces of heat and cold. Nor can any one take occasion from Telesius to say, that a certain por tion of heat and cold is assigned to each natural site, according to a fixed analogy. And that it can thus happen, that though there be no additional heat or cold, yet if the space of the body of matter be extended or contracted, the thing would return to the same state, because more or less

made it plain that the influence of changing site does not depend, in a remarkable degree, upon heat and cold, when yet this is that very influence which assigns the greatest power to these principles. Those two influences follow which are universally recognised, through which bodies seek masses or greater congregations of things connatural with them, in observing of which, as of other subjects, men either trifle or err. For the vulgar school thinks it sufficient to have distinguished the natural from the forced motion, and to give out that heavy bodies are, by a natural motion, borne downward; light, upward. But these speculations are of very little help to philosophy. For their "nature," "art," "force," are only terms of terms and trifles. They should refer this motion not only to nature, but should seek in this very motion the particular and proper bias and inclination of the natural body. For there are many other natural motions, according to very different passive natures of things from these. The subject, therefore, is to be laid down according to these differences. Nay, those very motions which they call violent, are more truly natural than that which they call natural; if that be more according to nature which is more powerful, or even which is more of a universal kind. For that motion of ascent and descent is not very potent, nor even universal, but as it were provincial, and for certain regions, and even yielding and subjected to other motions. Their saying that heavy bodies are borne downward, light, upward, is no more than saying that heavy are heavy, light, light bodies. For what is so predicated is assumed from the very force of the term in the subject. But if by heavy they mean dense, by light, rare, they do not advance the subject, only they lead it back rather to the adjunct and concomitant, than to the cause. But they who so explain the bias of heavy bodies as to assert that they are borne to the earth's centre, and light to the circumference and circuit of heaven, as to their proper destinations, certainly advance something, and hint at a cause, but yet with much inconsideration. For places are not influences, nor is a body affected but by a body, and every incitation of a body which seems to be seat itself, affects and endeavours a configuration toward another body, not collocation or simple site, A. T. R.




I. Presence Tables.

We have first to note which are the substances, of whatever kind, that generate light; as stars, fiery meteors, flame, wood, metals, and other burning bodies, sugar in scraping or breaking it, the glowworm, the dews of salt water when it is agitated or scattered, the eyes of certain animals, some sorts of rotten wood, large quantities of snow; perhaps the air itself may possess a weak light adapted to the vision of the animals which see by night; iron and tin, when put into aqua fortis to be dissolved, boil, and without any fire produce intense heat, but whether or not they give out any light demands inquiry; the oil of lamps sparkles in very cold weather; a kind of faint light is sometimes observed in a clear night around a horse that is sweating; around the hair of certain persons, there is seen, though rarely, also a faint light, like a lambent flamule, as occured to Lucius Marcius in Spain; there was lately found an apron of a certain woman which was said to shine, yet only when rubbed; but it had been dyed in green, of which dye alum is an ingredient, and it rustled somewhat when shining. Whether alum shines or not when scraped or broken is matter of inquiry; but, I suppose, it requires more violent breaking, because it is firmer than sugar. In like manner, some stockings shine whilst you are pulling them off, whether from sweat or the dye of alum.

II. Absence Tables.

We must also observe which are the substances that give no light, yet have much similitude to such as do produce it. Boiling water does not give light; air though unusually heated does not give light; mirrors and diamonds, which so strikingly reflect light, give no light of their own. In this kind of instances we have also to consider diligently the instances migratory, namely, when light, as if transient, is present, and when absent. A burning coal gives light, but loses it instantly when strongly compressed; the crystalline humour of the glowworm, after the worm's death, even when broken and divided into parts, retains light for a short time, which, however, soon after fades away

III. Table of Degrees.

We must remark which sorts of light are more intense and vibrating, which less: the flame of wood produces a strong light; the flame of spirit of wine, a weaker; the flame of coals when fully kindled, a very dim and scarcely visible light.

IV. Colours of Light.

We have to consider the colours of light, what they are, what not; some stars are white, others glittering, some red, some lead-coloured; the common sorts of flame are generally croceous, and among these the coruscations from the sky, and the sparks from flint, tend most to whiteness; the flame of sulphur is ceruleous and beautiful; but in some substances are purple flames. No green flames are observed: what most inclines to greenness, is that of the glowworm. Neither are there any crimson flames discovered: heated iron is red, but if heated somewhat more intensely, it becomes as it were white.

V. Reflections of Light.

We have to observe what bodies reflect light: as mirrors, water, polished metals, the moon, precious stones. All liquid bodies and such as have very equal smooth surfaces are somewhat bright; but brightness is a certain small degree of light.

We have to remark attentively, whether or not the light of one lucid body can be reflected by another lucid body; as if you took heated iron and opposed it to the sun's rays. For the reflections of light are reflected on, yet becoming gradually feebler, from mirror to mirror.

VI. Multiplication of Light.

The multiplication of light must next be considered: as by mirrors, perspectives, and the like, by which light may be sharpened and thrown to a distance, or also rendered subtler and softer for distinguishing visible objects; as you may see among painters, who use a phial filled with water beside their candle.

Whether all bodies of any considerable size do not reflect light, must also be considered. For light, as may be believed, either goes through or is reflected: from which cause the moon, though


it be an opaque body, may yet reflect light by | light at all were present. Thus the visible body reason of its magnitude.

We must ascertain, too, whether or not the aggregation of lucid bodies multiplies light. And in regard to bodies equally lucid there is no doubt of this but it remains for inquiry, whether or not a light, which is evidently overcome and rendered of itself invisible by a greater light, doth not yet add some light, Whatsoever is bright also contributes somewhat of light, for an apartment is much lighter when hung with silk than with cloth. Light is also multiplied by refraction; for gems when cut into angles, and glass when broken, shine much more than if they were smooth.

VII. Modes of destroying Light.

The modes of destroying light must also be remarked as by the exuberance of greater light, and by dense and opaque mediums. The sun's rays certainly, falling on the flame of a fire, make the flame seem like a kind of whiter smoke.

VIII. Operations or Effects of Light. We have to consider the operations or effects of light, which, it seems, are few, and possess little power of changing bodies, especially solids. Light above all things generates itself, other qualities sparingly. Light doth certainly in some measure attenuate the air, is grateful to the spirits of animals, and exhilirates them; it excites the slumbering rays of all colours and visible things, for every colour is the broken image of light.

IX. Continuance of Light.

The continuance of light must be investigated; which, as it appears, is momentary. For light doth not illuminate an apartment more when it hath continued there for many hours, than for any single moment; which is not so in respect of heat, &c.; for the first portion of heat remains, Yet, twilight is by some thought to arise from the traces of

and a new one is added to it.

the sun.

X. Ways and Progress of Lagat. We have attentively to consider the ways and progress of light. Light is shed around on all sides; but it remains for inquiry whether it at the same time ascends a little, or is equally shed around, upwards, and downwards. The light itself generates light everywhere around it; so that when the body of light, on interposing a screen, is not discerned, yet the light itself illuminates every thing around, except the objects which fall within the shadow of the screen: these, however, receive some light from the light which is thrown around; for any thing within the shadow of the screen can be discerned much better than if no

of any lucid object, and the light itself, seem to be things different. Light doth not penetrate bodies which are fibrous and of unequal structure; but yet is not impeded by the solid hardness of a substance, as you shall see in glass and the like. Thus the straight line and the pores which are not transverse, alone seem to transmit light. The best conductor of light is air, which conveys light the better the purer it is. It remains for inquiry whether or not light is carried through the body of the air. Sounds certainly we see carried by winds, so that they may be heard farther when going with the wind than against it. But it remains for inquiry whether or not any thing of the kind takes place with light.

XI. Transparency of Lucid Bodies.

We must also inquire respecting the transparency of lucid bodies. The wick of a candle is seen within the flame; but through larger flames objects reach not the sight. But again, all transparency is lost on heating any body, as may be seen in glass, which is no longer transparent when heated. The substance of air is transparent, also of water; yet, these two transparent substances when mixed, as in snow or foam, are no longer transparent, but acquire a certain light

of their own.

XII. Cognations and Hostilitics of Light.

The cognations, and also the hostilities of light must be investigated. Light, as far as regards its production, has most of all cognation with three things, heat, tenuity, and motion. We must, these three with light, also the degrees of these therefore, consider the marriages and divorces of same marriages and divorces. The flame of spirit heat than red-hot iron, but a stronger light. of wine or of an ignis fatuus, has a much feebler Glowworms, and the dews of salt water, and of the things which we mentioned, throw out light, yet are not hot to the touch. Also burning metals are not subtile bodies, but yet they have an ardent heat. But, on the other hand, air is one of the subtlest bodies, yet it is void of light; again, this same air, and also winds, though rapid in motion, afford no light. But, on the other hand, burning metals do not lay aside their sluggish motion, nevertheless vibrate light.


But in the cognations of light, which have no relation to its production, but only to its progression, nothing is so much allied to it as sound. To the sympathies and disagreements of the two we must therefore strictly direct our attention.

In the following they agree: both light and sound are diffused around on all sides. Light and sound are conveyed through very largo spaces; but light more swiftly, as we see in can nons, where the light is sooner discerned than the

on one side of a wall is heard on the other side not much weaker. Sound also is heard within the septa of solid bodies, though fainter, as in the case of sounds within bloodstones; or when bodies are struck under water. But light is not at all visible in a solid, opaque body, which is close on all sides.

Light penetrates deeper than sound, as at the bottom of waters. Every sound is produced in the motion and manifest collision of bodies: not so light.

sound is heard, although the flame follows after. | from its nearness, doth also somewhat illustrate Both light and sound undergo the subtlest dis- the air behind the screen. But a sound excited tinctions; as sounds in words articulate, and light in the images of all visible objects. Light and sound produce, or generate almost nothing, except in the senses and spirits of animals. Light and sound are easily generated, and soon fade away. For there is no cause why any one should conceive that the sound, which continues for some time after a bell or chord has been struck, is produced at the moment of percussion; because, if you touch the bell or chord, the sound instantly ceases, from which it is evident, that the continuance of the sound is created by succession. One light is destroyed by a greater, as one sound by a greater, &c. But light and sound differ, in that light, as observed, is more rapid than sound, and goes over larger spaces: whether or not light is conveyed in the body of the air, in the same manner as sound, is uncertain: light proceeds in straight lines only, but sound in crooked lines, and in all directions. For where any thing is discerned in the shadow of a screen, there is no cause to think that the light penetrates the screen, but only that it illuminates the air around, which,

But hostilities of light, or privations, if any like the term better, occur not. However, as is exceedingly probable, the torpor of bodies, in their parts, is very inimical to light. For almost nothing gives light that is not in its own nature remarkably mobile, or excited by heat, or motion, or vital spirit.

Yet I always mean, that not only other instances remain to be investigated, (for these few we have adduced only by way of example,) but also that new topical articles, as the nature of things requires, may be added.




MAN, the servant and interpreter of nature, does | him, who can induce an effect upon certain suband understands as much as he has actually or stances only of such as are susceptible, is likementally observed of the order of nature: he wise imperfect. neither knows nor can do more.

The naked hand of man, however strong and constant, suffices for but few operations, and those easy; the same, by help of instruments, performs many and obstinate operations: so is it also with the mind.

The instruments of the hand excite or direct motion and the instruments of the mind prompt or caution the intellect.

On a given basis of matter to impose any nature, within the limits of possibility, is the intention of human power. In like manner, to know the causes of a given effect, in whatever subject, is the intention of human knowledge: which intentions coincide. For that which is in contemplation as a cause, is in operation as a medium.

The knowledge of him who knows the cause of any nature, as of whiteness or of heat, in certain subjects only, is imperfect. And the power of

He who knows the causes of any nature in some subjects only, knows the efficient or materiate cause, which causes are inconstant, and nothing else but vehicles and causes conveying form. But he who comprehends the unity of nature in the most dissimilar substances, knows the form of things.

He who knows the efficient and materiate causes, composes or divides things previously invented, or transfers and produces them; also in matter somewhat similar, he attaineth unto new inventions; the more deeply fixed limits of things he moveth not.

He who knows the forms, discloses and educes things which have not hitherto been done, such as neither the vicissitudes of nature, nor the diligence of experience might ever have brought into action, or as might not have entered into man's thoughts.

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