This happens, among other cases, whenever any object excites contrary passions. For it is observable that an opposition of passions commonly causes a new emotion in the spirits, and produces more disorder, than the concurrence of any two affections of equal force. This new emotion is easily converted into the predominant passion, and encreases its violence, beyond the pitch it would have arrived at had it met with no opposition. Hence we naturally desire what is forbid, and take a pleasure in performing actions, merely because they are unlawful. The notion of duty, when opposite to the passions, is seldom able to overcome them; and when it fails of that effect, is apt rather to encrease them, by producing an opposition in our motives and principles.

The same effect follows whether the opposition arises from internal motives or external obstacles. The passion commonly acquires new force and violence in both cases.

The efforts, which the mind makes to surmount the obstacle, excite the spirits and inliven the passion.

Uncertainty has the same influence as opposition. The agitation of the thought; the quick turns it makes from one view to another; the variety of passions, which succeed each other, according to the different views; All these produce an agitation in the mind, and transfuse themselves into the predominant passion.

There is not in my opinion any other natural cause, why security diminishes the passions, than because it removes that uncertainty, which encreases them. The mind, when left to itself, immediately languishes; and in order to preserve its ardour, must be every moment supported by a new flow of passion. For the same reason, despair, though contrary to security, has a like influence.

It is certain nothing more powerfully animates any affection, than to conceal some part of its object by throwing it into a kind of shade, which at the same time that it chews enough to pre-possess us in favour of the object, leaves still some work for the imagination. Besides that obscurity is always attended with a kind of uncertainty; the effort, which the fancy makes to compleat the idea, rouzes the spirits, and gives an additional force to the passion.

As despair and security, though contrary to each other, produce the same effects; so absence is observed to have contrary effects, and in different circumstances either encreases or diminishes our affections. The Duc de La Rochefoucault has very well observed, that absence destroys weak passions, but encreases strong; as the wind extinguishes a candle, but blows up a fire. Long absence naturally weakens our idea, and diminishes the passion: But where the idea is so strong and lively as to support itself, the uneasiness, arising from absence, encreases the passion and gives it new force and violence.

But nothing has a greater effect both to encrease and diminish our passions, to convert pleasure into pain, and pain into pleasure, than custom and repetition. Custom has two original effects upon the mind, in bestowing a facility in the performance of any action or the conception of any object; and afterwards a tendency or inclination towards it; and from these we may account for all its other effects, however extraordinary.

When the soul applies itself to the performance of any action, or the conception of any object, to which it is not accustomed, there is a certain unpliableness in the faculties, and a difficulty of the spirit's moving in their new direction. As this difficulty excites the spirits, it is the source of wonder, surprize, and of all the emotions, which arise from novelty; and is in itself very agreeable, like every thing, which inlivens the mind to a moderate degree. But though surprize be agreeable in itself, yet as it puts the spirits in agitation, it not only augments our agreeable affections, but also our painful, according to the foregoing principle, that every emotion, which precedes or attends a passion, is easily converted into it. Hence every thing, that is new, is most affecting, and gives us either more pleasure or pain, than what, strictly speaking, naturally belongs to it. When it often returns upon us, the novelty wears off; the passions subside; the hurry of the spirits is over; and we survey the objects with greater tranquillity.

By degrees the repetition produces a facility of the human mind, and an infallible source of pleasure, where the facility goes not beyond a certain degree. And here it is remarkable that the pleasure, which arises from a moderate facility, has not the same tendency with that which arises from novelty, to augment the painful, as well as the agreeable affections. The pleasure of facility does not so much consist in any ferment of the spirits, as in their orderly motion; which will sometimes be so powerful as even to convert pain into pleasure, and give us a relish in time what at first was most harsh and disagreeable.

But again, as facility converts pain into pleasure, so it often converts pleasure into pain, when it is too great, and renders the actions of the mind so faint and languid, that they are no longer able to interest and support it. And indeed, scarce any other objects become disagreeable through custom; but such as are naturally attended with some emotion or affection, which is destroyed by the too frequent repetition. One can consider the clouds, and heavens, and trees, and stones, however frequently repeated, without ever feeling any aversion. But when the fair sex, or music, or good cheer, or any thing, that naturally ought to be agreeable, becomes indifferent, it easily produces the opposite affection.

But custom not only gives a facility to perform any action, but likewise an inclination and tendency towards it, where it is not entirely disagreeable, and can never be the object of inclination. And this is the reason why custom encreases all active habits, but diminishes passive, according to the observation of a late eminent philosopher. The facility takes off from the force of the passive habits by rendering the motion of the spirits faint and languid. But as in the active, the spirits are sufficiently supported of themselves, the tendency of the mind gives them new force, and bends them more strongly to the action.

It is remarkable, that the imagination and affections have close union together, and that nothing, which affects the former, can be entirely indifferent to the latter. Wherever our ideas of good or evil acquire a new vivacity, the passions become more violent; and keep pace with the imagination in all its variations. Whether this proceeds from the principle above-mentioned, that any attendant emotion is easily converted into the predominant, I shall not determine. It is sufficient for my present purpose, that we have many instances to confirm this influence of the imagination upon the passions.

Any pleasure, with which we are acquainted, affects us more than any other, which we own to be superior, but of whose nature we are wholly ignorant. Of the one we can form a particular and determinate idea: The other we conceive under the general notion of pleasure; and it is certain, that the more general and universal any of our ideas are, the less influence they have upon the imagination. A general idea, though it be nothing but a particular one considered in a certain view, is commonly more obscure; and that because no particular idea, by which we represent a general one, is ever fixed or determinate, but may easily be changed for other particular ones, which will serve equally in the representation.

There is a noted passage in the history of Greece, which may serve for our present purpose. Themistocles told the Athenians, that he had formed a design, which would be highly useful to the public, but which it was impossible for him to communicate to them without ruining the execution, since its success depended entirely on the secrecy with which it should be conducted. The Athenians, instead of granting him full power to act as he thought fitting, ordered him to communicate his design to Aristides, in whose prudence they had an entire confidence, and whose opinion they were resolved blindly to submit to. The design of Themistocles was secretly to set fire to the fleet of all the Grecian commonwealths, which was assembled in a neighbouring port, and which being once destroyed would give the Athenians the empire of the sea without any rival Aristides returned to the assembly, and told them, that nothing could be more advantageous than the design of Themistocles but at the same time that nothing could be more unjust: Upon which the people unanimously rejected the project.

A late celebrated historian[1] admires this passage of antient history, as one of the most singular that is any where to be met.

[1] Mons. Rollin {Charles Rollin, HISTOIRE ANCIENNE.(Paris 1730-38)}.

"Here," says he, "they are not philosophers, to whom it is easy in their schools to establish the finest maxims and most sublime rules of morality, who decide that interest ought never to prevail above justice. It is a whole people interested in the proposal which is made to them, who consider it as of importance to the public good, and who notwithstanding reject it unanimously, and without hesitation, merely because it is contrary to justice."

For my part I see nothing so extraordinary in this proceeding of the Athenians. The same reasons, which render it so easy for philosophers to establish these sublime maxims, tend, in part, to diminish the merit of such a conduct in that people. Philosophers never ballance betwixt profit and honesty, because their decisions are general, and neither their passions nor imaginations are interested in the objects. And though in the present case the advantage was immediate to the Athenians, yet as it was known only under the general notion of advantage, without being conceived by any particular idea, it must have had a less considerable influence on their imaginations, and have been a less violent temptation, than if they had been acquainted with all its circumstances: Otherwise it is difficult to conceive, that a whole people, unjust and violent as men commonly are, should so unanimously have adhered to justice, and rejected any considerable advantage.

Any satisfaction, which we lately enjoyed, and of which the memory is fresh and recent, operates on the will with more violence, than another of which the traces are decayed, and almost obliterated. From whence does this proceed, but that the memory in the first case assists the fancy and gives an additional force and vigour to its conceptions? The image of the past pleasure being strong and violent, bestows these qualities on the idea of the future pleasure, which is connected with it by the relation of resemblance.

A pleasure, which is suitable to the way of life, in which we are engaged, excites more our desires and appetites than another, which is foreign to it. This phænomenon may be explained from the same principle.

Nothing is more capable of infusing any passion into the mind, than eloquence, by which objects are represented in their strongest and most lively colours. We may of ourselves acknowledge, that such an object is valuable, and such another odious; but until an orator excites the imagination, and gives force to these ideas, they may have but a feeble influence either on the will or the affections.

But eloquence is not always necessary. The bare opinion of another, especially when inforced with passion, will cause an idea of good or evil to have an influence upon us, which would otherwise have been entirely neglected. This proceeds from the principle of sympathy or communication; and sympathy, as I have already observed, is nothing but the conversion of an idea into an impression by the force of imagination.