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engagement, is in a great measure proportioned to the figure that the injured perfon makes; the vows and proteftations of lovers are an illustrious example of this obfervation, for thefe commonly are little regarded when made to women of inferior rank.

CHAP.

237

TH

CHA P. V.

MOTION AND FORCE.

HAT motion is agreeable to the eye without relation to purpose or design, may appear from the amusement it gives to infants: juvenile exercises are relished chiefly up

on that account.

If a body in motion be agreeable, one will be apt to conclude, that at reft it must be difagreeable: but we learn from experience, that this would be a rash conclufion. Reft is one of thofe circumstances that are neither agreeable nor difagreeable, being viewed with perfect indifferency. And happy it is for mankind that the matter is fo ordered: if reft were agreeable, it would difincline us to motion, by which all things are performed: if it were difagreeable, it would be a fource of perpetual uneafinefs; for the bulk of the things we fee, appear to be at reft. A fimilar inftance of defigning wisdom I have had occafion to explain, in oppofing grandeur to littleness, and elevation to lownefs of place. Even in the fimpleft matters, the finger of God is confpicuous: the happy adjustment

• See chap. 4.

of

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of the internal nature of man to his external cir

cumstances, difplay'd in the inftances here given,

is indeed admirable.

Motion is certainly agreeable in all its varieties of quicknefs and flowness; but motion long continued admits fome exceptions. That degree or continued motion which corresponds to the natural courfe of our perceptions, is the moft agreeable *. The quickest motion is for an inftant delightful: but it foon appears to be too rapid: it becomes painful, by forcibly accelerating the courfe of our perceptions. Slow continued motion becomes difagreeable for an oppofite reafon, that it retards the natural course of our perceptions †.

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

Motion uniformly accelerated, resembling an afcending feries of numbers, is more agreeable than when uniformly retarded: motion upward is agreeable by the elevation of the moving body. What then shall we fay of downward motion regularly accelerated by the force of gravity, com

*See chap. 9.

+ This will be explained more fully afterward, ch. 9.

pared

pared with upward motion regularly retarded by Which of thefe is the most a

the fame force?

greeable? This question is not easily folved.

but we

Motion in a straight line is agreeable prefer undulating motion, as of waves, of a flame, of a fhip under fail: fuch motion is more free, and alfo more natural. Hence the beauty of a ferpentine river.

The eafy and fliding motion of fluids, from the lubricity of their parts, is agreeable upon that account: but the agreeablenefs chiefly depends upon 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 ftruck with this beauty, draw more images from fluids in motion than from folids.

Force is of two kinds; one quiefcent, and one exerted in motion. The former, dead weight for example, must be laid aside; for a body at reft is not by that circumftance either agreeable or difagreeable. Moving force only belongs to the present fubject; and though it is not feparable from motion, yet by the power of abftraction, either of them may be confidered independent of the other. Both of them are agreeable, because both of them include activity. It is agreeable to see a thing move to fee it moved, as when it is dragged or pufhed along, is neither agreeable nor difagreeable, more than when at reft. It is agreeable to fee a thing exert force; but it makes

not

not the thing either agreeable or difagreeable, to fee force exerted upon it.

Though motion and force are each of them agreeable, the impreffions they make are different. This difference, clearly felt, is not easily defcribed. All we can fay is, that the emotion raised by a moving body, refembling its caufe, is felt as if the mind were carried along the emotion raifed by force exerted, resembling alfo its caufe, is felt as if force were exerted within the mind.

To illuftrate this difference, I give the following examples. It has been explained why smoke afcending in a calm day, fuppofe from a cottage in a wood, is an agreeable object *; fo remarkably agreeable, that landscape-painters introduce it upon all occafions. The afcent being natural, and without effort, is delightful in a calm ftate of mind it refembles a gently-flowing river, but is more agreeable, because ascent is more to our tafte than defcent. A fire-work or a jet d'eau roufes the mind more; because the beauty of force visibly exerted, is fuperadded to that of upward motion. To a man reclining indolently upon a bank of flowers, afcending fmoke in a ftill morning is delightful; but a fire-work or a jet d'eau roufes him from this fupine posture, and puts him in motion.

A jet d'eau makes an impreffion diftinguishable from that of a water-fall. Downward motion

* Chap. I.

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