Aristotle makes wisdom, prudence, good sense, science, and art, as well as the moral virtues and vices, to be habits. If he meant no more, by giving this name to all those intellectual and moral qualities, than that they are all strengthened and confirmed by repeated acts, this is undoubtedly true. I take the word in a less extensive sense, when I consider habits as principles of action. I conceive it to be a part of our constitution, that what we have been accustomed to do, we acquire, not only a facility, but a proneness to do on like occasions; so that it requires a particular will and effort to forbear it; but to do it, requires very often no will at all. We are carried by habit as by a stream in swimming, if we make no resistance.

Every art furnishes examples, both of the power of habits and of their utility; no one more than the most common of all arts, the art of speaking.

Articulate language is spoken, not by nature, but by art. It is no easy matter to children, to learn the simple sounds of language; I mean, to learn to pronounce the vowels and consonants. It would be much more difficult, if they were not led by instinct to imitate the sounds they hear; for the difficulty is vastly greater of teaching the deaf to pronounce the letters and words, though experience shows that it can be done.

What is it that makes this pronunciation so easy at last which was so difficult at first? It is habit.

But from what cause does it happen, that a good speaker no sooner conceives what he would express, than the letters, syllables, and words arrange themselves according to innumerable rules of speech, while he never thinks of these rules? He means to express certain sentiments; in order to do this properly, a selection must be made of the materials out of many thousands. He makes this selection without any expense of time or thought. The materials selected must be arranged in a particular order, according to innumerable rules of grammar, logic, and rhetoric, and accompanied with a particular tone and emphasis. He does all this as it were by inspiration, without thinking of any of these rules, and without breaking one of them.

This art, if it were not more common, would appear more wonderful, than that a man should dance blindfold amidst a thousand burning ploughshares, without being burnt; yet all this may be done by habit.

It appears evident, that as, without instinct, the infant could not live to become a man, so, without habit, man would remain an infant through life, and would be as helpless, as unhandy, as speechless, and as much a child in understanding at threescore as at three.

I see no reason to think, that we shall ever be able to assign the physical cause. either of instinct, or of the power of habit.

Both seem to be parts of our original constitution. Their end and use is evident; but we can assign no cause of them, but the will of him who made us.

With regard to instinct, which is a natural propensity, this will perhaps be easily granted; but it is no less true with regard to that power and inclination which we acquire by habit.

No man can show a reason why our doing a thing frequently should produce either facility or inclination to do it.

The fact is so notorious, and so constantly in our eye, that we are apt to think no reason should be sought for it, any more than why the sun shines. But there must be a cause of the sun's shining, and there must be a cause of the power of habit.

We see nothing analogous to it in inanimate matter, or in things made by human art. A clock or a watch, a wagon or a plough, by the custom of going, does not learn to go better, or require less moving force. The earth does not increase in fertility by the custom of bearing crops.

It is said, that trees and other vegetables, by growing long in an unkindly soil or climate, sometimes acquire qualities by which they can bear its inclemency with less hurt. This, in the vegetable kingdom, has some resemblance to the power of habit; but in inanimate matter, I know nothing that resembles it.

A stone loses nothing of its weight by being long supported, or made to move upward. A body, by being tossed about ever so long, or ever so violently, loses nothing of its inertia, nor acquires the least disposition to change its state.

ESSAY III.

OF THE PRINCIPLES OF ACTION.

PART II.

OF ANIMAL PRINCIPLES OF ACTION.

CHAPTER I.

OF APPETITES.

HAVING discoursed of the mechanical principles of action, I proceed to consider those I called animal.

They are such as operate upon the will and intention, but do not suppose any exercise of judgment or reason; and are most of them to be found in some brute animals, as well as in man.

In this class, the first kind I shall call appetites, taking that word in a stricter sense than it is sometimes taken, even by good writers.

The word appetite is sometimes limited, so as to signify only the desire of food when we hunger; sometimes it is extended so as to signify any strong desire, whatever be its object. Without pretending to censure any use of the word which custom has authorized, I beg leave to limit it to a particular class of desires, which are distinguished from all others by the following marks.

1st, Every appetite is accompanied with an uneasy sensation proper to it, which is strong or weak, in proportion to the desire we have of the object. 2dly, Appetites are not constant, but periodical, being sated by their objects for a time, and returning after certain periods. Such is the nature of those principles of action to which I beg leave, in this Essay, to appropriate the name of appetites. Those that are chiefly observable in man, as well as in most other animals, are hunger, thirst, and lust.

If we attend to the appetite of hunger, we shall find in it two ingredients, an uneasy sensation and a desire to eat. The de

sire keeps pace with the sensation, and ceases when it ceases. When a man is sated with eating, both the uneasy sensation and the desire to eat cease for a time, and return after a certain interval. So it is with other appetites.

In infants, for some time after they come into the world, the uneasy sensation of hunger is probably the whole. We cannot suppose in them, before experience, any conception of eating, nor consequently, any desire of it. They are led by mere instinct to suck when they feel the sensation of hunger. But when experience has connected, in their imagination, the uneasy sensation with the means of removing it, the desire of the last comes to be so associated with the first, that they remain through life inseparable and we give the name of hunger to the principle that is made up of both.

That the appetite of hunger includes the two ingredients I have mentioned, will not, I apprehend, be questioned. I take notice of it the rather because we may, if I mistake not, find a similar composition in other principles of action. They are made up of different ingredients, and may be analyzed into the parts that enter into their composition.

If one philospher should maintain, that hunger is an uneasy sensation, another, that it is a desire to eat, they seem to differ widely; for a desire and a sensation are very different things, and have no similitude. But they are both in the right; for hunger includes both an uneasy sensation and a desire to eat.

Although there has been no such dispute among philosophers as we have supposed with regard to hunger, yet there have been similar disputes with regard to other principles of action; and it deserves to be considered whether they may not be terminated in a similar manner.

The ends for which our natural appetites are given, are too evident to escape the observation of any man of the least reflection. Two of those I named are intended for the preservation of the individual, and the third for the continuance of the species.

The reason of mankind would be altogether insufficient for these ends, without the direction and call of appetite.

Though a man knew that his life must be supported by eating, reason could not direct him when to eat, or what; how much, or how often. In all these things, appetite is a much better guide than our reason. Were reason only to direct us in this matter, its calm voice would often be drowned in the hurry of business, or the charms of amusement. But the voice of appetite rises gradually, and, at last, becomes loud enough to call off our attention from any other employment.

Every man must be convinced, that, without our appetites, even supposing mankind inspired with all the knowledge requisite for answering their ends, the race of men must have perish

ed long ago; but, by their means, the race is continued from one generation to another, whether men be savage or civilized, knowing or ignorant, virtuous or vicious.

By the same means, every tribe of brute animals, from the whale that ranges the ocean to the least microscopic insect, has been continued from the beginning of the world to this day; nor has good evidence been found, that any one species which God made has perished.

Nature has given to every animal, not only an appetite for its food, but taste and smell, by which it distinguishes the food proper for it.

It is pleasant to see a caterpillar, which nature intended to live upon the leaf of one species of plant, travel over a hundred leaves of other kinds without tasting one, till it comes to that which is its natural food, which it immediately falls on, and devours greedily.

Most caterpillars feed only upon the leaf of one species of plant, and nature suits the season of their production to the food that is intended to nourish them. Many insects and animals have a greater variety of food; but of all animals, man has the greatest variety, being able to subsist upon almost every kind of vegetable or animal food, from the bark of trees to the oil of whales.

I believe our natural appetites may be made more violent by excessive indulgence, and that, on the other hand, they may be weakened by starving. The first is often the effect of a pernicious luxury, the last may sometimes be the effect of want, sometimes of superstition. I apprehend that nature has given to our appetites that degree of strength which is most proper for us; and that whatever alters their natural tone, either in excess or in defect, does not mend the work of nature, but may mar and pervert it.

A man may eat from appetite only. So the brutes commonly do. He may eat to please his taste when he has no call of appetite. I believe a brute may do this also. He may eat for the sake of health, when neither appetite nor taste invites. This, as far as I am able to judge, brutes never do.

From so many different principles, and from many more, the same action may be done; and this may be said of most human actions. From this, it appears, that very different and contrary theories may serve to account for the actions of men. causes assigned may be sufficient to produce the effect, and yet not be the true causes.

The

To act merely from appetite, is neither good nor ill in a moral view. It is neither an object of praise nor of blame. No man claims any praise because he eats when he is hungry, or rests when he is weary. On the other hand, he is no object of