XXV

Among Prerogative Instances I will put in the fourth place Clandestine Instances, which I also call Instances of the Twilight, and which are pretty nearly the opposites of Striking Instances. For they exhibit the nature under investigation in its lowest degree of power, and as it were in its cradle and rudiments; striving indeed and making a sort of first attempt, but buried under and subdued by a contrary nature. Such instances, however, are of very great service for the discovery of forms; because as striking instances lead easily to specific differences, so are clandestine instances the best guides to genera, that is, to those common natures whereof the natures proposed are nothing more than particular cases.

For example, let the nature proposed be consistency, or the nature of that which determines its own figure, opposed to which is fluidity. Those are clandestine instances which exhibit some feeble and low degree of consistency in a fluid: as a bubble of water, which is a sort of consistent pellicle of determined figure, made of the body of the water. Of a similar kind are the droppings from a house, which if there be water to follow, lengthen themselves out into a very thin thread to preserve the continuity of the water; but if there be not water enough to follow, then they fall in round drops, which is the figure that best preserves the water from a solution of continuity. But at the very moment of time when the thread of water ceases and the descent in drops begins, the water itself recoils upward to avoid discontinuation. Again in metals, which in fusion are liquid but more tenacious, the molten drops often fly to the top and stick there. A somewhat similar instance is that of children's looking glasses, which little boys make on rushes with spittle, where also there is seen a consistent pellicle of water. This, however, is much better shown in that other childish sport when they take water, made a little more tenacious by soap, and blow it through a hollow reed, and so shape the water into a sort of castle of bubbles which by the interposition of the air become so consistent as to admit of being thrown some distance without discontinuation. But best of all is it seen in frost and snow, which assume such a consistency that they can be almost cut with a knife, although they are formed out of air and water, both fluids. All which facts not obscurely intimate that consistent and fluid are only vulgar notions, and relative to the sense; and that in fact there is inherent in all bodies a disposition to shun and escape discontinuation; but that it is faint and feeble in homogeneous bodies (as fluids), more lively and strong in bodies compounded of heterogeneous matter; the reason being that the approach of heterogeneous matter binds bodies together, while the insinuation of homogeneous matter dissolves and relaxes them.

To take another instance, let the proposed nature be the attraction or coming together of bodies. In the investigation of its form the most remarkable striking instance is the magnet. But there is a contrary nature to the attractive; namely, the nonattractive, which exists in a similar substance. Thus there is iron which does not attract iron, just as lead does not attract lead, nor wood wood, nor water water. Now a clandestine instance is a magnet armed with iron, or rather the iron in an armed magnet. For it is a fact in nature that an armed magnet at some distance off does not attract iron more powerfully than an unarmed magnet. But if the iron be brought so near as to touch the iron in the armed magnet, then the armed magnet supports a far greater weight of iron than a simple and unarmed magnet, on account of the similarity of substance between the pieces of iron; an operation altogether clandestine and latent in the iron before the magnet was applied. Hence it is manifest that the form of coition is something which is lively and strong in the magnet, feeble and latent in iron. Again, it has been observed that small wooden arrows without an iron point, discharged from large engines, pierce deeper into wooden material (say the sides of ships, or the like) than the same arrows tipped with iron, on account of the similarity of substance between the two pieces of wood; although this property had previously been latent in the wood. In like manner, although air does not manifestly attract air or water water in entire bodies, yet a bubble is more easily dissolved on the approach of another bubble than if that other bubble were away, by reason of the appetite of coition between water and water, and between air and air. Such clandestine instances (which, as I have said, are of the most signal use) exhibit themselves most conspicuously in small and subtle portions of bodies; the reason being that larger masses follow more general forms, as shall be shown in the proper place.