ESSAY III.

OF THE PRINCIPLES OF ACTION.

PART I.

OF THE MECHANICAL PRINCIPLES OF ACTION.

CHAPTER I.

OF THE PRINCIPLES OF ACTION IN GENERAL.

IN the strict philosophical sense, nothing can be called the action of a man, but what he previously conceived and willed or determined to do. In morals we commonly employ the word in this sense, and never impute any thing to a man as his doing, in which his will was not interposed. But when moral imputation is not concerned, we call many things actions of the man, which he neither previously conceived nor willed. Hence the actions of men have been distinguished into three classes, the voluntary, the involuntary, and the mixed. By the last are meant such actions as are under the command of the will, but are commonly performed without any interposition of will.

We cannot avoid using the word action in this popular sense, without deviating too much from the common use of language; and it is in this sense we use it when we inquire into the principles of action in the human mind.

By principles of action, I understand every thing that incites us to act. If there were no incitements to action, active power would be given us in vain. Having no motive to direct our active exertions, the mind would, in all cases, be in a state of perfect indifference, to do this or that, or nothing at all. The active power would either not be exerted at all, or its exertions would be perfectly unmeaning and frivolous, neither wise nor foolish, neither good nor bad. To every action that is of the smallest importance, there must be some incitement, some motive, some reason.

It is therefore a most important part of the philosophy of the human mind, to have a distinct and just view of the various principles of action, which the Author of our being hath planted in our nature, to arrange them properly, and to assign to every one its rank.

By this it is, that we may discover the end of our being, and the part which is assigned us upon the theatre of life. In this part of the human constitution, the noblest work of God that falls within our notice, we may discern most clearly the character of him who made us, and how he would have us to employ that active power which he hath given us.

I cannot without great diffidence enter upon this subject, observing that almost every author of reputation, who has given attention to it, has a system of his own; and that no man has been so happy as to give general satisfaction to those who came after him.

There is a branch of knowledge much valued, and very justly, which we call knowledge of the world, knowledge of mankind, knowledge of human nature: This, I think, consists in knowing from what principles men generally act; and it is commonly the fruit of natural sagacity joined with experience.

A man of sagacity, who has had occasion to deal in interesting matters, with a great variety of persons of different age, sex, rank, and profession, learns to judge what may be expected from men in given circumstances; and how they may be most effectually induced to act the part which he desires. To know this is of so great importance to men in active life, that it is called knowing men, and knowing human nature.

This knowledge may be of considerable use to a man who would speculate upon the subject we have proposed, but is not, by itself, sufficient for that purpose.

The man of the world conjectures, perhaps with great probability, how a man will act in certain given circumstances; and this is all he wants to know. To enter into a detail of the various principles which influence the actions of men, to give them distinct names, to define them, and to ascertain their different provinces, is the business of a philosopher, and not of a man of the world; and, indeed, it is a matter attended with great difficulty from various causes.

First, On account of the great number of active principles that influence the actions of men.

Man has, not without reason, been called an epitome of the universe. His body, by which his mind is greatly affected, being a part of the material system, is subject to all the laws of inanimate matter. During some part of his existence, his state is very like that of a vegetable. He rises, by imperceptible degrees, to the animal, and, at last, to the rational life, and has the principles that belong to all.

Another cause of the difficulty of tracing the various principles of action in man, is, That the same action, nay, the same course and train of action, may proceed from very different principles.

Men who are fond of an hypothesis, commonly seek no other proof of its truth, but that it serves to account for the appearances which it is brought to explain. This is a very slippery kind of proof in every part of philosophy, and never to be trusted; but least of all, when the appearances to be accounted for are human actions.

Most actions proceed from a variety of principles concurring in their direction; and according as we are disposed to judge favourably or unfavourably of the person, or of human fiature in general, we impute them wholly to the best, or wholly to the worst, overlooking others which had no small share in them.

The principles from which men act can be discovered only in these two ways; by attention to the conduct of other men, or by attention to our own conduct, and to what we feel in ourselves. There is much uncertainty in the former, and much difficulty in the latter.

Men differ much in their characters; and we can observe the conduct of a few only of the species. Men differ not only from other men, but from themselves at different times, and on different occasions; according as they are in the company of their superiors, inferiors, or equals; according as they are in the eye of strangers, or of their familiars only, or in the view of no human eye; according as they are in good or bad fortune, or in good or bad humour. We see but a small part of the actions of our most familiar acquaintance; and what we see may lead us to a probable conjecture, but ean give no certain knowledge of the principles from which they act.

A man may, no doubt, know with certainty the principles from which he himself acts, because he is conscious of them. But this knowledge requires an attentive reflection upon the operations of his own mind, which is very rarely to be found. It is perhaps more easy to find a man who has formed a just notion of the character of man in general, or of those of his familiar acquaintance, than one who has a just notion of his own character. Most men, through pride and self-flattery, are apt to think themselves better than they really are; and some, perhaps from melancholy or from false principles of religion, are led to think themselves worse than they really are.

It requires, therefore, a very accurate and impartial examination of a man's own heart to be able to form a distinct notion of the various principles which influence his conduct. That this is a matter of great difficulty, we may judge from the very different and contradictory systems of philosophers upon this subject, from the earliest ages to this day.

During the age of Greek philosophy, the Platonist, the Peripatetic, the Stoic, the Epicurean, had each his own system. In the dark ages, the Schoolmen and the Mystics had systems diametrically opposite; and, since the revival of learning, no controversy hath been more keenly agitated, especially among British philosophers, than that about the principles of action in the human constitution.

They have determined, to the satisfaction of the learned, the forces by which the planets and comets traverse the boundless regions of space; but have not been able to determine, with any degree of unanimity, the forces which every man is conscious of in himself, and by which his conduct is directed.

Some admit no principle but self-love; others resolve all into love of the pleasures of sense, variously modified by the association of ideas; others admit disinterested benevolence along with self-love; others reduce all to reason and passion; others to passion alone; nor is there less variety about the number and distribution of the passions.

The names we give to the various principles of action, have so little precision even in the best and purest writers in every language, that, on this account, there is no small difficulty in giving them names, and arranging them properly.

The words appetite, passion, affection, interest, reason, cannot be said to have one definite signification. They are taken sometimes in a larger, and sometimes in a more limited sense. The same principle is sometimes called by one of those names, sometimes by another; and principles of a very different nature are often called by the same name.

To remedy this confusion of names, it might perhaps seem proper to invent new ones. But there are so few entitled to this privilege, that I shall not lay claim to it; but shall endeavour to class the various principles of human action as distinctly as I am able, and to point out their specific differences; giving them such names as may deviate from the common use of the words as little as possible.

There are some principles of action which require no attention, no deliberation, no will. These, for distinction's sake, we shall call mechanical. Another class we may call animal, as they seem common to man with other animals. A third class we may call rational, being proper to man as a rational creature.

CHAPTER II.

OF INSTINCT.

THE mechanical principles of action may, I think, be reduced to two species, instincts and habits.

By instinct, I mean a natural blind impulse to certain actions, without having any end in view, without deliberation, and very often without any conception of what we do.

Thus a man breathes while he is alive, by the alternate contraction and relaxation of certain muscles, by which the chest, and of consequence, the lungs, are contracted and dilated. There is no reason to think, that an infant new-born knows that breathing is necessary to life in its new state, that he knows how it must be performed, or even that he has any thought or conception of that operation; yet he breathes as soon as he is born with perfect regularity, as if he had been taught, and got the habit by long practice.

By the same kind of principle, a new-born child, when its stomach is emptied, and nature has brought milk into the mother's breast, sucks and swallows its food as if it knew the principles of that operation, and had got the habit of working according to them.

Sucking and swallowing are very complex operations. Anatomists describe about thirty pairs of muscles that must be employed in every draught. Of those muscles, every one must be served by its proper nerve, and can make no exertion but by some influence communicated by the nerve. The exertion of all those muscles and nerves is not simultaneous. They must succeed each other in a certain order, and their order is no less necessary than the exertion itself.

This regular train of operations is carried on according to the nicest rules of art, by the infant, who has neither art, nor science, nor experience, nor habit.

That the infant feels the uneasy sensation of hunger, I admit; and that it sucks no longer than till this sensation be removed. But who informed it that this uneasy sensation might be removed, or by what means? That it knows nothing of this is evident; for it will as readily suck a finger, or a bit of stick, as the nipple.

By a like principle it is, that infants cry when they are pained or hurt; that they are afraid when left alone, especially in the dark; that they start when in danger of falling; that they are terrified by an angry countenance, or an angry tone of voice, and are soothed and comforted by a placid countenance, and by soft and gentle tones of voice.

In the animals we are best acquainted with, and which we look upon as the more perfect of the brute creation, we see much the same instincts as in the human kind, or very similar ones, suited to the particular state and manner of life of the animal.

Besides these, there are in brute animals instincts peculiar to each tribe, by which they are fitted for defence, for offence, or for providing for themselves and for their offspring.

It is not more certain, that nature hath furnished various animals with various weapons of offence and defence, than that the same nature hath taught them how to use them; the bull and the ram to butt, the horse to

kick, the dog to bite, the lion to use his paws, the boar his tusks, the serpent his fangs, and the bee and wasp their sting.

The manufactures of animals, if we may call them by that name, present us with a wonderful variety of instincts, belonging to particular species, whether of the social or of the solitary kind: the nests of birds, so similar in their situation and architecture in the same kind, so various in different kinds; the webs of spiders, and of other spinning animals; the ball of the silk-worm; the nests of ants and other mining animals; the combs of wasps, hornets and bees; the dams and houses of beavers.

The instinct of animals is one of the most delightful and instructive parts of a most pleasant study, that of natural history; and deserves to be more cultivated than it has yet been.

Every manufacturing art among men was invented by some man, improved by others, and brought to perfection by time and experience. Men learn to work in it by long practice, which produces a habit. The arts of men vary in every age, and in every nation, and are found only in those who have been taught them.

The manufactures of animals differ from those of men in many striking particulars.

No animal of the species can claim the invention. No animal ever introduced any new improvement, or any variation from the former practice. Every one of the species has equal skill from the beginning, without teaching, without experience, or habit. Every one has its art by a kind of inspiration. I do not mean that it is inspired with the principles or rules of the art, but with the ability and inclination of working in it to perfection, without any knowledge of its principles, rules, or end.

The more sagacious animals may be taught to do many things which they do not by instinct. What they are taught to do, they do with more or less skill, according to their sagacity and their training. But, in their own arts, they need no teaching nor training, nor is the art ever improved or lost. Bees gather their honey and their wax, they fabricate their combs, and rear their young at this day, neither better nor worse than they did when Virgil so sweetly sang their works.

The work of every animal is indeed like the works of nature, perfect in its kind, and can bear the most critical examination of the mechanic or the mathematician. One example from the animal last mentioned may serve to illustrate this.

Bees, it is well known, construct their combs with small cells on both sides, fit both for holding their store of honey, and for rearing their young. There are only three possible figures of the cells, which can make them all equal and similar, without any useless interstices. These are the equilateral triangle, the square, and the regular hexagon.

It is well known to mathematicians, that there is not a fourth way possible, in which a plane may be cut into little spaces that shall be equal, similar and regular, without leaving any interstices. Of the three, the hexagon is the most proper, both for conveniency and strength. Bees, as if they knew this, make their cells regular hexagons.

As the combs have cells on both sides, the cells may either be exactly opposite, having partition against partition, or the bottom of a cell may rest upon the partitions between the cells on the other side, which will serve as a buttress to strengthen it. The last way is best for strength; accordingly the bottom of each cell rests against the point where three partitions meet on the other side, which gives it all the strength possible.

The bottom of a cell may either be one plane perpendicular to the side