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CHAPTER V.

Motion and Force.

THAT motion is agreeable to the eye withont relation to purpose or design, may appear from the amusement it gives to infants : juvenile exercises are relished chiefly on that account.

If a body in motion be agreeable, one will be apt to conclude that at rest it must be disagreeable: but we learn from experience, that this would be a rash conclusion. Rest is one of those circumstances that are neither agreeable nor disagreeable, being viewed with perfect indifferency. And happy is it for mankind to have the matter so ordered ; if rest were agreeable, it would disincline us to mo. tion, by which all things are performed : if it were disagreeable, it would be a source of perpetual uneasiness; for the bulk of the things we see, appear to be at rest. A similar instance of designing wis. dom I have had occasion to explain, in opposing grandeur to littleness, and elevation to lowness of place.* Even in the simplest matters, the finger of God is conspicuous: the happy adjustment of the internal nature of man to his external circumstances, displayed in the instances here given, is indeed admirable.

Motion is agreeable in all its varieties of quickness and slowness; but motion long continued admits some exceptions. That degree of continued motion which corresponds to the natural course of our perceptions, is the most agreeable. The quickest motion is for an instant delightful ; but soon appears to be too rapid : it becomes painful by for. cibly accelerating the course of our perceptions. Slow continued motion becomes disagreeable from an opposite cause, that it retards the natural course of our perceptions. *

* See Chapter IV.

There are other varieties in motion, beside quickness and slowness, that make it more or less agreeable : regular motion is preferred before what is irregular; witness the motion of the planets in orbits nearly circular: the motion of the comets in orbits less regular, is less agreeable.

Motion uniformly accelerated, resembling an as. cending series of numbers, is more agreeable than when uniformly retarded : motion opward is agreeable, by tendency to elevation. What then shall we say of downward motion regularly accelerated by the force of gravity, compared with upward motion regularly retarded by the same force? Which of these is the most agreeable? This question is not easily solved.

Motion in a straight line is agreeable : but we prefer undulating motion, as of waves, of a flame, of a ship under sail; such motion is more free, and also more natural. Hence the beauty of a serpentine river.

The easy and sliding motion of a fluid, from the lubricity of its parts, is agreeable upon that ac. count: but the agreeableness chiefly depends on the following circumstance, that the motion is perceived, not as of one body, but as of an endless number moving together with order and regularity. Poets struck with that beauty, draw more images from fluids in motion than from solids.

* This will be explained more fully afterward, chapter IX.

Force is of two kinds; one quiescent, and one exerted in motion. The former, dead weight for example, must be laid aside ; for a body at rest is not, by that circumstance, either agreeable or disa. greeable. Moving force only is my province; and, though it is not separable from motion, yet by the power of abstraction, either of them may be consi. dered independent of the other. Both of them are agreeable, because both of them include activity. It is agreeable to see a thing move: to see it moved; as when it is dragged or pushed along, is neither agreeable nor disagreeable, more than when at rest. It is agreeable to see a thing exert force; but it makes not the thing either agreeable or disagreeable, to see force exerted upon it.

Though motion and force are each of them agreeable, the impressions they make are different. This difference, clearly felt, is not easily described. All we can say is, that the emotion raised by a moving body, resembling its cause, is felt as if the mind were carried along : the emotion raised by force exerted, resembling also its cause, is felt as if force were exerted within the mind.

To illustrate that difference, I give the following examples. It has been explained why smoke ascending in a calm day, suppose from a cottage in a wood, is an agreeable object;* so remarkably agreeable, that landscape-painters iutroduce it upon all occasions. The ascent being natural, and without effort, is pleasant in a calm state of mind : it resembles a gently-flowing river, but is more agreeable, because ascent is more to our taste than descent. A fire-work or a jet d'eau rouses the mind more; because the beauty of force visibly exerted, is superadded to that of upward motion. To a man

* Chapter 1.

reclining indolently upon a bank of flowers, ascending smoke in a still morning is charming; but a fire-work or a jet d'eau rouses him from that supine posture, and puts him in motion.

A jet d'eau makes an impression distinguishable from that of a waterfall. Downward motion being natural and without effort, tends rather to quiet the mind than to rouse it: upward motion on the contrary, overcoming the resistance of gravity, makes an impression of a great effort, and thereby rouses and enlivens the mind.

The public games of the Greeks and Romans, which gave so much entertainment to the spectators, consisted chiefly in exerting force, wrestling, leaping, throwing great stones, and such-like trials of strength. When great force is exerted, the effort felt internally is animating. The effort may be such, as in some measure to overpower the mind : thus the explosion of gun-powder, the violence of a torrent, the weight of a mountain, and the crush of an earthquake, create astonishment rather than plea

sure,

No quality nor circumstance contributes more to grandeur than force, especially where exerted by sensible beings. I cannot make the observation more evident than by the following quotations.

-Him the almighty power
Hurl'd headlong flaming from th' ethereal sky,
With hideous ruin and combustion, down
To bottomless perdition, there to dwell
In adamantine chaijis and penal fire,
Who durst defy th' Omnipotent to arms.

Paradise Lost, book i.

Now storming fury rose,
And clamour such as heard in heaven till now
Was never; arms on armour clashing bray'd
Horrible discord, and the madding wheels

Ot brazen chariots rag'd; dire was the noise
Of conflict; over head the dismal hiss
Of fiery darts in flaming vollies flew,
And flying vaulted either host with fire.
So under fiery cope together rush'd
Both battles main, with ruinous assault
And inextinguishable rage; all heaven
Resounded ; and had earth been then, all earth
Had to her centre shook.

Ibid. book vi.

They ended parley, and both addressed for fight
Unspeakable ; for who, though with the tongue
Of angels, can relate, or to what things
Liken on earth conspicuous, that may lift
Human imagination to such height
Of godlike pow'r? for likest gods they seem'd,
Stood they or mov’d, in stature, motion, arms,
Fit to decide the empire of great Heav'n.
Now wav'd their fiery swords, and in the air
Made horrid circles: two broad suns their shields
Blaz'd opposite, while Expectation stood
In horror: from each hand with speed retir'd,
Where erst was thickest fight, th' angelic throng,
And left large field, unsafe within the wind
Of such commotion; such as, to set forth
Great things by small, if Nature's concord broke,
Among the constellations war were sprung,
Two planets, rushing from aspect malign
Of fiercest opposition, in mid sky
Should combat, and their jarring spheres confound.

Ibid. book vi,

We shall next consider the effect of motion and force in conjunction. In contemplating the planetary system, what strikes us the most, is the spherical figures of the planets, and their regular motions; the conception we have of their activity and enormous bulk being more obscure : the beauty accord. ingly of that system, raises a more lively emotion than its grandeur. But if we could comprehend the whole system at one view, the activity and irresistible force of these immense bodies would fill us

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