Having viewed a train of perceptions as directed by nature, and the variations it is susceptible of from different necessary causes, we proceed to examine how far it is subjected to will; for that will hath some influence, more or less, is observed above. And first, the rate of succession may be retarded by insisting upon one object, and propelled by dismissing another before its time. But such voluntary mutations in the natural course of succession, have limits that cannot be extended by the most painful efforts. The mind circumscribed in its capacity, cannot, at the same instant, admit many perceptions; and when replete, it has no place for new perceptions till others be removed. For this reason, a voluntary change of perceptions cannot be instantaneous; and the time it requires sets bounds to the velocity of succession. On the other hand, the power we have to arrest a flying perception, is equally limited. The longer we detain any perception, the more difficulty we find in the operation; till, the difficulty becoming unsurmountable, we are forced to quit our hold, and to permit the train to take its usual course.
The power we have over this train as to uniformity and variety, is in some cases very great, in others very little. A train so far as composed of external objects, depends entirely on the place we occupy, and admits not more or less variety but by change of place. A train composed of ideas of memmory, is still less under our power. Objects which are connected, afford the mind an easy passage from one to another. They suggest each other in idea by the same means; and we cannot at will call up any idea that is not connected with the train[94]. But a train of ideas suggested by reading, may be varied at will, provided we have books in store.
This power which nature hath given us over our train of perceptions, may be greatly strengthened by proper discipline, and by an early application to business. Its improved strength is remarkable in those who have a strong genius for the mathematics: nor less remarkable in persons devoted to religious exercises, who pass whole days in contemplation, and impose upon themselves long and severe penances. It is not to be conceived, what length a habit of activity in affairs will carry some men. Let a stranger, or let any person to whom the sight is not familiar, attend the Chancellor of Great Britain through the labours but of one day, during a session of parliament: how great will be his astonishment! what multiplicity of law-business, what deep thinking, and what elaborate application to matters of government! The train of perceptions must in this great man be accelerated far beyond the common course of nature. Yet no confusion nor hurry; but in every article the greatest order and accuracy. Such is the force of habit! How happy is man, to have the command of a principle of action, that can elevate him so far above the ordinary condition of humanity[95]!
We are now ripe for considering a train of perceptions with respect to pleasure and pain: and to this speculation we must give peculiar attention, because it serves to explain the effects that uniformity and variety have upon the mind. A man is always in a pleasant state of mind, when his perceptions flow in their natural course. He feels himself free, light, and easy, especially after any forcible acceleration or retardation. On the other hand, the resistance felt in retarding or accelerating the natural course, excites a pain, which, though scarcely felt in small removes, becomes considerable toward the extremes. An aversion to fix on any single object for a long time, or to take in a multiplicity of objects in a short time, is remarkable in children; and equally so in men unaccustomed to business. A man languishes when the succession is very slow; and, if he grow not impatient, is apt to fall asleep. During a rapid succession, he hath a feeling as if his head were turning round. He is fatigued, and his pain resembles that of weariness after bodily labour. External objects, when they occasion a very slow or a very quick succession, produce a pain of the same sort with what it felt in a voluntary retardation or acceleration: which shows that the pain proceeds not from the violence of the action, but from the retardation or acceleration itself, disturbing that free and easy course of succession which is naturally pleasant.
But the mind is not satisfied with a moderate course alone: its perceptions must also be sufficiently diversified. Number without variety constitutes not an agreeable train. In comparing a few objects, uniformity is agreeable: but the frequent reiteration of uniform objects becomes unpleasant. One tires of a scene that is not diversified; and soon feels a sort of unnatural restraint when confined within a narrow range, whether occasioned by a retarded succession or by too great uniformity. An excess in variety is, on the other hand, fatiguing. This is even perceptible in a train composed of related objects: much more where the objects are unrelated; for an object, unconnected with the former train, gains not admittance without effort; and this effort, though scarce perceptible in a single instance, becomes by frequent reiteration exceeding painful. Whatever be the cause, the fact is certain, that a man never finds himself more at ease, than when his perceptions succeed each other with a certain degree, not only of velocity, but also of variety. Hence it proceeds, that a train consisting entirely of ideas of memory, is never painful by too great variety; because such ideas are not introduced otherwise than according to their natural connections[96]. The pleasure of a train of ideas, is the most remarkable in a reverie; especially where the imagination interposes, and is active in coining new ideas, which is done with wonderful facility. One must be sensible, that the serenity and ease of the mind in this state, makes a great part of the enjoyment. The case is different where external objects enter into the train; for these, making their appearance without any order, and without any connection save that of contiguity, form a train of perceptions that may be extremely uniform or extremely diversified; which, for opposite reasons, are both of them painful.
Any acceleration or retardation of the natural run of perceptions, is painful even where it is voluntary. And it is equally painful to alter that degree of variety which nature requires. Contemplation, when the mind is long attached to one thing, soon becomes painful by restraining the free range of perception. Curiosity and the prospect of advantage from useful discoveries, may engage a man to prosecute his studies, notwithstanding the pain they give him; and a habit of close attention, formed by frequent exercise, may soften the pain. But it is deeply felt by the bulk of mankind, and produceth in them an aversion to all abstract sciences. In any profession or calling, a train of operation that is simple and reiterated without intermission, makes the operator languish, and lose his vigor. He complains neither of too great labour nor of too little action; but regrets the want of variety, and his being obliged to do the same thing over and over. Where the operation is sufficiently varied, the mind retains its vigor, and is pleased with its condition. Actions again create an uneasiness when excessive in number or variety, though in every other respect agreeable. This uneasiness is extremely remarkable, where strict attention must be given, at the same time, to a number of different things. Thus a throng of business in law, in physic, or in traffick, distresseth and distracts the mind, unless where a habit of application is acquired by long and constant exercise. The excessive variety is the distressing circumstance; and the mind suffers grievously by being kept constantly upon the stretch.
With relation to involuntary causes disturbing that degree of variety which nature requires, a slight pain affecting one part of the body without variation, becomes, by its constancy and long duration, almost insupportable. The patient, sensible that the pain is not increased in degree, complains of its constancy more than of its severity, that it ingrosses his whole thoughts, and gives admission to no other object. Pain, of all feelings, seizes the attention with the greatest force; and the mind, after fruitless efforts to turn its view to objects more agreeable, must abandon itself to its tormentor. A shifting pain gives less uneasiness, because change of place contributes to variety. An intermitting pain, suffering other objects to intervene, is not increased by reiteration. Again, any single colour or sound often returning, becomes disagreeable; as may be observed in viewing a train of similar apartments painted with the same colour, and in hearing the prolonged tollings of a bell. Colour and sound varied within certain limits, though without any order, are agreeable; witness a field variegated with many colours of plants and flowers, and the various notes of birds in a thicket. Increase the number or variety, and the feeling becomes unpleasant. Thus a great variety of colours, crowded upon a small canvas or in quick succession, create an uneasy feeling, which is prevented by putting the colours at a greater distance either of place or time. A number of voices in a crowded assembly, a number of animals collected in a market, produce an unpleasant emotion; though a few of them together, or all of them in a moderate succession, would be agreeable. And because of the same excess in variety, a number of pains felt in different parts of the body, at the same instant or in a rapid succession, make an exquisite torture.
The foregoing doctrine concerning the train of perceptions, and the pleasure or pain resulting from that train in different circumstances, will be confirmed by attending to the final cause of these effects. And as I am sensible that the mind, inflamed with speculations of this kind so highly interesting, is beyond measure disposed to conviction, I shall be watchful to admit no argument nor remark but what appears solidly founded. With this caution I proceed to the inquiry. It is occasionally observed above, that persons of a phlegmatic temperament, having a sluggish train of perceptions, are indisposed to action; and that activity constantly accompanies a brisk motion of perceptions. To ascertain this fact, a man need not go abroad for experiments. Reflecting upon things passing in his own mind, he will find, that a brisk circulation of thought constantly prompts him to action; and that he is averse to action when his perceptions languish in their course. But man by nature is formed for action, and he must be active in order to be happy. Nature therefore hath kindly provided against indolence, by annexing pleasure to a moderate course of perceptions, and by making every remarkable retardation painful. A slow course of perceptions is attended with another bad effect. Man in a few capital cases is governed by propensity or instinct; but in matters that admit deliberation and choice, reason is assigned him for a guide. Now, as reasoning requires often a great compass of ideas, their succession ought to be so quick, as readily to furnish every motive that may be necessary for mature deliberation. In a languid succession, motives will often occur after action is commenced, when it is too late to retreat.
Nature hath guarded man, her favourite, against a succession too rapid, not less carefully than against one too slow. Both are equally painful, though the pain is not the same in both. Many are the good effects of this contrivance. In the first place, as the bodily faculties are by certain painful sensations confined within proper limits, beyond which it would be dangerous to strain the tender organs, Nature, in like manner, is equally provident with respect to the nobler faculties of the mind. Thus the pain of an accelerated course of perceptions, is Nature’s admonition to relax our pace, and to admit a more gentle exertion of thought. Another valuable purpose may be gathered, from considering in what manner objects are imprinted upon the mind. To make such an impression as to give the memory fast hold of the object, time is required, even where attention is the greatest; and a moderate degree of attention, which is the common case, must be continued still longer to produce the same effect. A rapid succession then must prevent objects from making impressions so deep as to be of real service in life; and Nature accordingly for the sake of memory, has by a painful feeling guarded against a rapid succession. But a still more valuable purpose is answered by this contrivance. As, on the one hand, a sluggish course of perceptions indisposeth to action; so, on the other, a course too rapid impels to rash and precipitant action. Prudent conduct is the child of deliberation and clear conception, for which there is no place in a rapid course of thought. Nature therefore, taking measures for prudent conduct, has guarded us effectually from precipitancy of thought, by making it painful.
Nature not only provides against a succession too slow or too quick, but makes the middle course extremely pleasant. Nor is this middle course confined within narrow bounds. Every man can naturally without pain accelerate or retard in some degree the rate of his perceptions; and he can do this in a still greater degree by the force of habit. Thus a habit of contemplation annihilates the pain of a retarded course of perceptions; and a busy life, after long practice, makes acceleration pleasant.