VI.

On Apparent Rest, Consistency, and Fluidity.

That certain bodies appear at rest and deprived of motion, seems correct if applied to the whole or entire body, but if to the parts erroneous. For simple and absolute rest, both in the parts and the whole, there is none; but that which is thought to be so is the effect of some hindrance, prevention and equilibrium of motions. For instance, in garden watering-pots, which are pierced full of holes at the bottom, the water (if the mouth of the pot be stopped up) does not run out at the bottom; and this evidently proceeds from a retractive motion, not from a quiescent nature. For the water tries to descend, as much as if it had the power to do so; but there being nothing at the top of the pot to take its place, the water at the bottom is drawn back and forcibly detained by the water at the top. For if in wrestling the stronger man holds down the weaker, so that he cannot move, yet, if the weaker still resist with all his strength, the motion of resistance is not therefore less, because it does not prevail, and is held fast by the stronger motion. Now this which I say of false rest, as in innumerable things it is useful to be known, so it sheds no small light on the inquiry of the nature of solid and liquid, or consistency an fluidity. For solids seem to be stationary and at rest in their positions, but liquids to move about and be in confusion; for you cannot raise a column or other statue of water as you can of wood or stone. Therefore it is natural to suppose that the upper parts of the water strive (by a motion which they call natural) to flow downwards; but that with the parts of wood it is

different. This however is not true; as there is the same motion downwards in the upper parts of wood as in water; and this would be carried into action, if it were not held and drawn back by a more powerful motion. Now this is certainly the desire of continuity, or the avoidance of separation, which betongs to water as well as to wood, but in wood is stronger than the motion of gravity, in water weaker. For that even liquids participate in this motion is manifest. In bubbles we see the water throw itself into thin films of a hemispherical form to avoid separation. In droppings we see the water, to continue itself, is drawn out and attenuated into a fine thread, as long as there is any water to succeed; but if there be a deficiency in the continuation, then the water forms itself into round drops, whereof the diameter is much greater than the previous thread. In like manner we see water does not readily submit to a very subtle comminution of its parts, since it will not of its own natural weight, without concussion, run out of very fine holes and cracks. Whence it is evident that in liquids there is an appetite of continuity, though a weak one; whereas on the contrary, in solids it is strong, and overpowers the natural motion or gravity. For if a man think that in a pillar of wood or stone the upper parts do not desire to flow downwards, but to support themselves exactly in the same state, he will easily correct his mistake by observing that pillars or the like, if their height be not in proportion to the width of their base, but exceed it, cannot stand, but are borne down by their weight; so that very high buildings must incline to a pyramidal form, and be narrower towards the top. But what that nature is which increases or lessens this desire of

continuity will not easily be found on inquiry. It will perhaps be suggested that the parts of solids are denser and more compact; the parts of liquids rarer and looser; or that liquids have a spirit which is a principle of fluidity that is wanting in solids, and the like. But neither of these is in accordance with truth. For it is manifest that snow and wax, which may be cut and moulded and take impressions, are far rarer than quicksilver or melted lead, as is proved in the proportion of their gravities. But if a man still insist that snow or wax, though rarer (in the whole) than quicksilver, may yet have closer and more compact parts; but that because their bodies are spongy, and have many cavities, and admit the air, they are therefore in the whole lighter; as is the case in the pumice-stone, which in proportion to its size may perhaps be lighter than wood, yet if both be reduced to powder, the powder of pumice-stone will be heavier than that of wood, because it has now lost its cavities; his observations and objections are good. But what will they say to melted snow and wax, where the cavities are already filled up? or what to the bodies of gums, mastich, and the like, which have not these manifest cavities, and yet are lighter than many fluids? Now what they allege of the spirit, the power and force whereof make things flow, is certainly at first sight probable, and familiar to common notions; but in reality it is more difficult and erroneous, as being not only not supported by reason, but almost opposed to it. For this spirit they talk of does in fact (though it may appear strange) produce consistency, and not fluidity.

And this is excellently shown in the instance of snow, which though a body compounded of water and air, and though air

But

and water separate are fluids, yet acquires consistency by mixture. But if a man object that this may perhaps proceed from a condensation of the watery part by cold, and not from the interposition of the air, he may correct his opinion by observing that foam also is a body like snow, which yet is no way condensed by cold. But if he still urge that in foam likewise condensation proceeds not from cold, but from agitation and percussion, let him look at the boys who, out of a little air breathed through a pipe or tube, and water mixed with a little soap, to make it more tenacious, raise a wonderful tower-like fabric of bubbles. the fact is that bodies, at the touch of a body that is friendly or similar, resolve and open themselves; but at the touch of an unfriendly body they shrink up and gather themselves together. And hence the apposition of an alien body is the cause of consistency. Thus we see that when oil is mixed with water, the transparency which existed before both in the oil and the water is to a certain extent lost. On the other hand, we see that paper moistened with water resolves itself and loses its consistency (which before by reason of the air in its pores was strong); but moistened with oil it does it less, because oil less with paper. agrees The same likewise we see in sugar and like bodies, which relax themselves to receive water or wine, and that not only when the liquids press upon them, but they likewise suck and draw up the liquids themselves.

VII.

On the Consent between Sensible and Insensible Bodies. The passions of bodies which have sense, and of bodies without sense, have a great correspondence,

except that a sensible body has also a spirit. For the pupil of the eye is like a looking-glass, or water, and receives and reflects the images of light and visible bodies in the same manner. The organ of hearing has a conformity with an obstruction in a cave, from which the voice and sound is best re-echoed.. The attraction of things inanimate, and again the horrors and aversions (I speak of such as are proper and peculiar) in animals, correspond to the sense of smell and pleasing and disagreeable odours. In the taste and touch we find every kind either of violence on the one hand or of gentle and friendly insinuation on the other which can happen in inanimate bodies, with all the configurations of these same passions, expressed and interpreted. For in dead bodies compressions, extensions, corrosions, separations, and the like are concealed in their process, and only perceived in their manifest effects. But in animals they are performed with a sensation of pain, according to the different kind and character of the violence, the spirit pervading everything. And from this principle is derived the knowledge whether any animal may possibly have some other sense besides those observed; and how many, and what kind of senses there may be in the whole race of animals. For a just distinction of the passions of matter will give the number of senses, provided only that the requisite organs be supplied, and the spirit be added.

VIII.

On Violent Motion, that it is the flight and dispersion of the parts of a thing from pressure, though not visible. Violent motion (as they call it), whereby projectiles, as stones, arrows, bullets, and the like, fly through the