XL

Among Prerogative Instances I will put in the seventeenth place Summoning Instances, borrowing the name from the courts of law, because they summon objects to appear which have not appeared before. I also call them Evoking Instances. They are those which reduce the nonsensible to the sensible, that is, make manifest things not directly perceptible by means of others which are.

An object escapes the senses either on account of its distance; or on account of the interposition of intermediate bodies; or because it is not fitted for making an impression on the sense; or because it is not sufficient in quantity to strike the sense; or because there is not time enough for it to act on the sense; or because the impression of the object is such as the sense cannot bear; or because the sense has been previously filled and occupied by another object, so that there is not room for a new motion. These cases have reference principally to the sight, and secondarily to the touch. For these two senses give information at large and concerning objects in general, whereas the other three give hardly any information but what is immediate and relates to their proper objects.

In the first kind, where an object is imperceptible by reason of its distance, there is no way of manifesting it to the sense but by joining to it or substituting for it some other object which may challenge and strike the sense from a greater distance — as in communication by beacons, bells, and the like.

In the second kind, this reduction or secondary manifestation is effected when objects that are concealed by the interposition of bodies within which they are enclosed and cannot conveniently be opened out are made manifest to the sense by means of those parts of them which lie on the surface, or make their way from the interior. Thus the condition of the human body is known by the state of the pulse, urine, and the like.

In the third and fourth kind, reductions are applicable to a great many things, and in the investigations of nature should be sought for on all sides. For example, it is obvious that air and spirit, and like bodies, which in their entire substance are rare and subtle, can neither be seen nor touched. Therefore, in the investigation of bodies of this kind it is altogether necessary to resort to reductions.

Thus let the nature in question be the action and motion of the spirit enclosed in tangible bodies. For everything tangible that we are acquainted with contains an invisible and intangible spirit which it wraps and clothes as with a garment. Hence that three-fold source, so potent and wonderful, of the process of the spirit in a tangible body. For the spirit in a tangible substance, if discharged, contracts bodies and dries them up; if detained, softens and melts them; if neither wholly discharged nor wholly detained, gives them shape, produces limbs, assimilates, digests, ejects, organizes, and the like. And all these processes are made manifest to the sense by conspicuous effects.

For in every tangible inanimate body the enclosed spirit first multiplies itself and, as it were, feeds upon those tangible parts which are best disposed and prepared for that purpose and so digests and elaborates and turns them into spirit; and then they escape together. Now this elaboration and multiplication of the spirit is made manifest to the sense by diminution of weight. For in all desiccation there is some decrease of quantity, not only of the quantity of spirit previously existing in the body, but also of the body itself, which was before tangible and is newly changed. For spirit is without weight. Now the discharge or emission of the spirit is made manifest to the sense in the rust of metals and other similar putrefactions which stop short before they come to the rudiments of life; for these belong to the third kind of process. For in compact bodies the spirit finds no pores or passages through which to escape and is therefore compelled to push and drive before it the tangible parts themselves, so that they go out along with it; whence proceed rust and the like. On the other hand the contraction of the tangible parts after some of the spirit is discharged (upon which desiccation ensues), is made manifest to the sense not only by the increased hardness of the body, but much more by the rents, contractions, wrinklings, and shrivelings in the body which thereupon take place. For the parts of wood split asunder and are contracted; skins shrivel; and not only that, but if the spirit is suddenly discharged by the heat of fire, they hasten so fast to contraction as to curl and roll themselves up.

On the contrary, where the spirit is detained and yet expanded and excited by heat or something analogous thereto (as happens in the more solid or tenacious bodies), then are bodies softened, as white hot iron; or they become fluid, as metals; or liquid, as gums, wax, and the like. Thus the contrary operations of heat, which hardens some substances and melts others, are easily reconciled, since in the former the spirit is discharged, in the latter it is excited and detained; whereof the melting is the proper action of the heat and spirit, the hardening is the action of the tangible parts only on occasion of the discharge of the spirit.

But when the spirit is neither wholly detained nor wholly discharged, but only makes trials and experiments within its prison house, and meets with tangible parts that are obedient and ready to follow, so that wheresoever the spirit leads they go along with it, then ensues the forming of an organic body and the development of organic parts, and all the other vital actions as well in vegetable as in animal substances. And these operations are made manifest to the sense chiefly by careful observation of the first beginnings and rudiments or essays of life in animalculae generated from putrefaction, as in ants' eggs, worms, flies, frogs after rain, etc. There is required, however, for the production of life both mildness in the heat and pliancy in the substance, that the spirit may neither be so hurried as to break out, nor be confined by the obstinacy of the parts, but may rather be able to mold and model them like wax.

Again, that most noble distinction of spirit which has so many applications (viz., spirit cut off; spirit simply branching; spirit at once branching and cellulate — of which the first is the spirit of all inanimate substances, the second of vegetables, the third of animals), is brought as it were before the eyes by several instances of this kind of reduction.

In like manner it appears that the more subtle textures and configurations of things (though the entire body be visible or tangible) are perceptible neither to the sight nor touch. And therefore in these also, our information comes by way of reduction. Now the most radical and primary difference between configurations is drawn from the abundance or scantiness of the matter occupying the same space or dimensions. For all other configurations (which have reference to the dissimilarity of the parts contained in the same body, and to their collocation and position) are but secondary in comparison with the former.

Thus let the nature in question be the expansion or coition of matter in bodies compared one with another, viz., how much matter occupies how much space in each. For there is nothing more true in nature than the twin propositions that "nothing is produced from nothing," and "nothing is reduced to nothing," but that the absolute quantum or sum total of matter remains unchanged, without increase or diminution. Nor is it less true that of that quantum of matter more or less is contained under the same space or dimensions according to the diversity of bodies; as in water more, in air less. So that to assert that a given volume of water can be changed into an equal volume of air is as much as to say that something can be reduced to nothing; as on the other hand to maintain that a given volume of air can be turned into an equal volume of water is the same as to say that something can be produced out of nothing. And it is from this abundance and scantiness of matter that the abstract notions of dense and rare, though variously and promiscuously used, are, properly speaking, derived. We must also take for granted a third proposition which is also sufficiently certain, viz., that this greater or less quantity of matter in this or that body is capable of being reduced by comparison to calculation and to exact or nearly exact proportions. Thus one would be justified in asserting that in any given volume of gold there is such an accumulation of matter, that spirit of wine, to make up an equal quantity of matter, would require twenty-one times the space occupied by the gold.

Now the accumulation of matter and its proportions are made manifest to the sense by means of weight. For the weight answers to the quantity of matter in the parts of a tangible body, whereas spirit and the quantum of matter which it contains cannot be computed by weight, for it rather diminishes the weight than increases it. But I have drawn up a very accurate table on this subject, in which I have noted down the weights and volumes of all the metals, the principal stones, woods, liquors, oils, and many other bodies, natural as well as artificial — a thing of great use in many ways, as well for light of information as for direction in practice, and one that discloses many things quite beyond expectation. Not the least important of which is this — it shows that all the variety in tangible bodies known to us (such bodies I mean as are tolerably compact and not quite spongy and hollow, and chiefly filled with air) does not exceed the limit of the ratio of 1 to 21 — so limited is nature, or at any rate that part of it with which we have principally to do.

I have also thought it worth while to try whether the proportions can be calculated which intangible or pneumatic bodies bear to bodies tangible. This I attempted by the following contrivance. I took a glass phial, capable of holding about an ounce, using a small vessel that less heat might be required to produce evaporation. This phial I filled with spirit of wine almost to the neck, selecting spirit of wine, because I found by the former table that of all tangible bodies (which are well united and not hollow) this is the rarest and contains the least quantity of matter in a given space. After that, I noted exactly the weight of the spirit and phial together. I then took a bladder capable of holding about a quart from which I squeezed out, as well as I could, all the air, until the two sides of the bladder met. The bladder I had previously rubbed over gently with oil, to make it closer, and having thus stopped up the pores, if there were any, I inserted the mouth of the phial within the mouth of the bladder, and tied the latter tightly round the former with a thread smeared with wax in order that it might stick more closely and tie more firmly. After this I set the phial on a chafing dish of hot coals. Presently the steam or breath of the spirit of wine, which was dilated and rendered pneumatic by the heat, began gradually to expand the bladder and swelled it out on all sides like a sail. When this took place, I immediately took the glass off the fire, placing it on a carpet that it might not crack with the cold, at the same time making a hole in the bladder lest the steam should turn liquid again on the cessation of the heat and so disturb the calculations. I then removed the bladder, and weighing the spirit of wine which remained, computed how much had been converted into steam or air. Then, comparing the space which the body had occupied while it was spirit of wine in the phial with the space which it afterward occupied when it had become pneumatic in the bladder, I computed the results, which showed clearly that the body had acquired by the change a degree of expansion a hundred times greater than it had had before.

Again, let the nature in question be heat or cold, in a degree too weak to be perceptible to the sense. These are made manifest to the sense by a calendar glass such as I have described above. For the heat and cold are not themselves perceptible to the touch, but the heat expands the air, and the cold contracts it. Nor again is this expansion and contraction of the air perceptible to the sight, but the expansion of the air depresses the water, the contraction raises it, and so at last is made manifest to the sight; not before, nor otherwise.

Again, let the nature in question be the mixture of bodies, viz., what they contain of water, oil, spirit, ash, salt, and the like; or (to take a particular instance) what quantity of butter, curd, whey, etc., is contained in milk. These mixtures, so far as relates to tangible elements, are made manifest to the sense by artificial and skillful separations. But the nature of the spirit in them, though not immediately perceived, is yet discovered by the different motions and efforts of the tangible bodies in the very act and process of their separation and also by the acridities and corrosions, and by the different colors, smells, and tastes of the same bodies after separation. And in this department men have labored hard, it is true, with distillations and artificial separations, but not with much better success than in the other experiments which have been hitherto in use. For they have but groped in the dark and gone by blind ways and with efforts painstaking rather than intelligent, and (what is worst of all), without attempting to imitate or emulate nature, but rather destroying by the use of violent heats and overstrong powers all that more subtle configuration in which the occult virtues and sympathies of things chiefly reside. Nor do they remember or observe, while making such separations, the circumstances which I have elsewhere pointed out, namely, that when bodies are tormented by fire or other means, many qualities are communicated by the fire itself and by the bodies employed to effect the separation which did not exist previously in the compound; whence strange fallacies have arisen. For it must not be supposed that all the vapor which is discharged from water by the action of fire was formerly vapor or air in the body of the water, the fact being that the greatest part of it was created by the expansion of the water from the heat of the fire.

So in general, all the nice tests of bodies whether natural or artificial by which the genuine are distinguished from the adulterated, the better from the viler sort, should be referred to this division; for they make manifest to the sense things not directly perceptible by means of those which are. They should therefore be sought and collected from all quarters with diligent care.

With regard to the fifth way in which objects escape the sense, it is obvious that the action of sense takes place in motion, and that motion takes place in time. If therefore the motion of any body be either so slow or so quick that it bears no proportion to the moments which the sense takes to act in, the object is not perceived at all, as in the motion of the hand of a clock and again in the motion of a musket ball. Now motion which is too slow to be perceived is easily and usually made manifest to the sense by means of aggregates of motion. Motion which is too quick has not hitherto been competently measured, and yet the investigation of nature requires that this be done in some cases.

In the sixth kind, where the sense is hindered by the too great power of the object, the reduction may be effected either by removing the object to a greater distance from the sense; or by deadening its effects by the interposition of a medium which will weaken without annihilating the object; or by admitting and receiving the reflection of the object where the direct impression is too powerful, as that of the sun, for instance, in a basin of water.

The seventh cause, where the sense is so charged with one object that it has no room for the admission of another, is almost wholly confined to the sense of smell and has little to do with the matter in hand. So much then for the reduction of the nonsensible to the sensible — or the modes of making manifest to the sense things not directly perceptible by means of others which are.

Sometimes, however, the reduction is made not to the sense of a man, but of some other animal whose sense in some cases is keener than man's; as of certain scents to the sense of a dog; of the light which is latent in air when not illumined from without to the sense of a cat, owl, and similar animals which see in the dark. For Telesius has justly observed that there is in the air itself a certain original light, though faint and weak, and hardly of any use to the eyes of men and most animals; inasmuch as animals to whose sense this light is adapted see in the dark, which it is hardly to be believed they do either without light, or by a light within.

Observe also that at present I am dealing with the deficiencies of the senses and their remedies. The deceptions of the senses must be referred to the particular inquiries concerning sense and the objects of sense, excepting only that grand deception of the senses, in that they draw the lines of nature with reference to man and not with reference to the universe; and this is not to be corrected except by reason and universal philosophy.