24: Wrestling Instances

24. Wrestling instances or instances of predominance

⁴⁸ These point out the predominance and submission of powers compared with each other, and which of them is the more energetic and superior, or more weak and inferior.

For the motions and effects of bodies are compounded, decomposed, and combined, no less than the bodies themselves.

The following are the principal kinds of motions:

1. The resistance of matter

This exists in every particle. It completely prevents its annihilation.

In this way, no conflagration, weight, pressure, violence, or length of time can:

• reduce even the smallest portion of matter to nothing
• prevent it from being something and occupy some space, and deliver itself by:
  • changing its form or place or
  • remaining as it is

Nor can it ever happen that it should either be nothing or nowhere.[245]

The schools generally name and define everything by its effects and inconveniences rather than by its inherent cause.

The schools call this motion by the axiom that 2 bodies cannot exist in the same place.

They call it a motion to prevent the penetration of dimensions.

It is useless to give examples of this motion, since it exists in every body.

2. The motion of connection

This motion delights in the mutual connection and contact between bodies.

It does not allow bodies to be separated from the contact of another body.

The schools call this as a motion to prevent a vacuum.

It happens when:

• water is drawn up by suction or a syringe
• the flesh by cupping, or
• the water remains without escaping from perforated jars, unless the mouth be opened to admit the air, and innumerable instances of a like nature.

3. The motion of liberty

This makes bodies strive:

• to deliver themselves from any unnatural pressure or tension
• restore themselves to the dimensions suited to their mass

There are innumerable examples of this as the escape from pressure:

• in the water in swimming
• in the air in flying
• in the water in rowing
• in the air in the undulation of the winds
• in springs of watches.

An exact instance of the motion of compressed air is seen in children’s popguns, which they make by scooping out elder-branches or some such matter, and forcing in a piece of some pulpy root or the like, at each end.

Then they force the root or other pellet with a ramrod to the opposite end, from which the lower pellet is emitted and projected with a report, and that before it is touched[246] by the other piece of root or pellet, or by the ramrod.

We have examples of their escape from tension, in the motion of the air that remains in glass eggs after suction, in strings, leather, and cloth, which recoil after tension, unless it be long continued.

The schools define this by the term of motion from the form of the element; injudiciously enough, since this motion is to be found not only in air, water, or fire, but in every species of solid, as wood, iron, lead, cloth, parchment, etc., each of which has its own proper size, and is with difficulty stretched to any other.

Since, however, this motion of liberty is the most obvious of all, and to be seen in an infinite number of cases, it will be as well to distinguish it correctly and clearly; for some most carelessly confound this with the two others of resistance and connection; namely, the freedom from pressure with the former, and that from tension with the latter, as if bodies when compressed yielded or expanded to prevent a penetration of dimensions, and when stretched rebounded and contracted themselves to prevent a vacuum.

But if the air, when compressed, could be brought to the density of water, or wood to that of stone, there would be no need of any penetration of dimensions, and yet the compression would be much greater than they actually admit of. So if water could be expanded till it became as rare as air, or stone as rare as wood, there would be no need of a vacuum, and yet the expansion would be much greater than they actually admit of.

We do not, therefore, arrive at a penetration of dimensions or a vacuum before the extremes of condensation and rarefaction, while the motion we speak of stops and exerts itself much within them, and is nothing more than a desire of bodies to preserve their specific density (or,[247] if it be preferred, their form), and not to desert them suddenly, but only to change by degrees, and of their own accord. It is, however, much more necessary to intimate to mankind (because many other points depend upon this), that the violent motion which we call mechanical, and Democritus (who, in explaining his primary motions, is to be ranked even below the middling class of philosophers) termed the motion of a blow, is nothing else than this motion of liberty, namely, a tendency to relaxation from compression. For in all simple impulsion or flight through the air, the body is not displaced or moved in space, until its parts are placed in an unnatural state, and compressed by the impelling force. When that takes place, the different parts urging the other in succession, the whole is moved, and that with a rotatory as well as progressive motion, in order that the parts may, by this means also, set themselves at liberty, or more readily submit. Let this suffice for the motion in question.

4. The motion of matter

This is opposed to the the motion of liberty.

In motion of liberty, bodies abhor, reject, and avoid, a new size or volume, or any new expansion or contraction (for these different terms have the same meaning), and strive, with all their power, to rebound and resume their former density;

on the contrary, in the motion of matter, they are anxious to acquire a new volume or dimension, and attempt it willingly and rapidly, and occasionally by a most vigorous effort, as in the example of gunpowder. The most powerful, or at least most frequent, though not the only instruments of this motion, are heat and cold. For instance, the air, if expanded by tension (as by suction in the glass egg), struggles[248] anxiously to restore itself; but if heat be applied, it strives, on the contrary, to dilate itself, and longs for a larger volume, regularly passing and migrating into it, as into a new form (as it is termed); nor after a certain degree of expansion is it anxious to return, unless it be invited to do so by the application of cold, which is not indeed a return, but a fresh change. So also water, when confined by compression, resists, and wishes to become as it was before, namely, more expanded; but if there happen an intense and continued cold, it changes itself readily, and of its own accord, into the condensed state of ice; and if the cold be long continued, without any intervening warmth (as in grottoes and deep caves), it is changed into crystal or similar matter, and never resumes its form.