The idea of ourselves is always intimately present to us, and conveys a sensible degree of vivacity to the idea of any other object to which we are related. This lively idea changes by degrees into a real impression; these two kinds of perception being in a great measure the same, and differing only in their degrees of force and vivacity. But this change must be produced with the greater ease, that our natural temper gives us a propensity to the same impression which we observe in others, and makes it arise upon any slight occasion. In that case resemblance converts the idea into an impression, not only by means of the relation, and by transfusing the original vivacity into the related idea; but also by presenting such materials as take fire from the least spark. And as in both cases a love or affection from the resemblance, we may learn that a sympathy with others is agreeable only by giving an emotion to the spirits, since an easy sympathy and correspondent emotions are alone common to relation, acquaintance, and resemblance.
The great propensity men have to pride may be considered as another similar phenomenon. It often happens, that after we have lived a considerable time in any city, however at first it might be disagreeable to us, yet as we become familiar with the objects, and contract an acquaintance, though merely with the streets and buildings, the aversion diminishes by degrees, and at last changes into the opposite passion. The mind finds a satisfaction and ease in the view of objects to which it is accustomed, and naturally prefers them to others, which, though perhaps in themselves more valuable, are less known to it. By the same quality of the mind we are seduced into a good opinion of ourselves, and of all objects that belong to us. They appear in a stronger light, are more agreeable, and consequently fitter subjects of pride and vanity than any other.
It may not be amiss, in treating of the affection we bear our acquaintance and relations, to observe some pretty curious phenomena which attend it. 'Tis easy to remark in common life, that children esteem their relation to their mother to be weakened, in a great measure, by her second marriage, and no longer regard her with the same eye as if she had continued in her state of widowhood. Nor does this happen only when they have felt any inconveniences from her second marriage, or when her husband is much her inferior; but even without any of these considerations, and merely because she has become part of another family. This also takes place with regard to the second marriage of a father, but in a much less degree; and 'tis certain the ties of blood are not so much loosened in the latter case as by the marriage of a mother. These two phenomena are remarkable in themselves, but much more so when compared.
In order to produce a perfect relation betwixt two objects, 'tis requisite, not only that the imagination be conveyed from one to the other, by resemblance, contiguity or causation, but also that it return back from the second to the first with the same ease and facility. At first sight this may seem a necessary and unavoidable consequence. If one object resemble another, the latter object must necessarily resemble the former. If one object be the cause of another, the second object is effect to its cause. 'Tis the same with contiguity; and therefore the relation being always reciprocal, it may be thought, that the return of the imagination from the second to the first must also, in every case, be equally natural as its passage from the first to the second. But upon farther examination we shall easily discover our mistake. For supposing the second object, beside its reciprocal relation to the first, to have also a strong relation to a third object; in that case the thought, passing from the first object to the second, returns not back with the same facility, though the relation continues the same, but is readily carried on to the third object, by means of the new relation which presents itself, and gives a new impulse to the imagination. This new relation, therefore, weakens the tie betwixt the first and second objects. The fancy is, by its very nature, wavering and inconstant, and considers always two objects as more strongly related together, where it finds the passage equally easy both in going and returning, than where the transition is easy only in one of these motions. The double motion is a kind of a double tie, and binds the objects together in the closest and most intimate manner.
The second marriage of a mother breaks not the relation of child and parent; and that relation suffices to convey my imagination from myself to her with the greatest ease and facility. But after the imagination is arrived at this point of view, it finds its object to be surrounded with so many other relations which challenge its regard, that it knows not which to prefer, and is at a loss what new object to pitch upon. The ties of interest and duty bind her to another family, and prevent that return of the fancy from her to myself which is necessary to support the union. The thought has no longer the vibration requisite to set it perfectly at ease, and indulge its inclination to change. It goes with facility, but returns with difficulty; and by that interruption finds the relation much weakened from what it would be were the passage open and easy on both sides.
Now, to give a reason why this effect follows not in in the same degree upon the second marriage of a father; we may reflect on what has been proved already, that though the imagination goes easily from the view of a lesser object to that of a greater, yet it returns not with the same facility from the greater to the less. When my imagination goes from myself to my father, it passes not so readily from him to his second wife, nor considers him as entering into a different family, but as continuing the head of that family of which I am myself a part. His superiority prevents the easy transition of the thought from him to his spouse, but keeps the passage still open for a return to myself along the same relation of child and parent. He is not sunk in the new relation he acquires; so that the double motion or vibration of thought is still easy and natural. By this indulgence of the fancy in its inconstancy, the tie of child and parent still preserves its full force and influence.
A mother thinks not her tie to a son weakened because 'tis shared with her husband; nor a son his with a parent, because 'tis shared with a brother. The third object is here related to the first as well as to the second: so that the imagination goes and comes along all of them with the greatest facility.