The Theory of Moral Sentiments by Adam Smith

As it is a divided sympathy which renders the whole set of passions just now mentioned, upon most occasions, so ungraceful and disagreeable: so there is another set opposite to these, which a redoubled sympathy renders almost always peculiarly agreeable and becoming. Generosity, humanity, kindness, compassion, mutual friendship and esteem, all the social and benevolent affections, when expressed in the countenance or behaviour, even towards those who are not peculiarly connected with ourselves, please the indifferent spectator upon almost every occasion. His sympathy with the person who feels those passions, exactly coincides with his concern for the person who is the object of them. The interest, which, as a man, he is obliged to take in the happiness of this last, enlivens his fellow-feeling with the sentiments of the other, whose emotions are employed about the same object. We have always, therefore, the strongest disposition to sympathize with the benevolent affections. They appear in every respect agreeable to us. We enter into the satisfaction both of the person who feels them, and of the person who is the object of them. For as to be the object of hatred and indignation gives more pain than all the evil which a brave man can fear from his enemies: so there is a satisfaction in the consciousness of being beloved, which, to a person of delicacy and sensibility, is of more importance to happiness, than all the advantage which he can expect to derive from it. What character is so detestable as that of one who takes pleasure to sow dissention among friends, and to turn their most tender love into mortal hatred? Yet wherein does the atrocity of this so much abhorred injury consist? Is it in depriving them of the frivolous good offices, which, had their friendship continued, they might have expected from one another? It is in depriving them of that friendship itself, in robbing them of each other's affections, from which both derived so much satisfaction; it is in disturbing the harmony of their hearts, and putting an end to that happy commerce which had before subsisted between them. These affections, that harmony, this commerce, are felt, not only by the tender and the delicate, but by the rudest vulgar of mankind, to be of more importance to happiness than all the little services which could be expected to flow from them.

The sentiment of love is, in itself, agreeable to the person who feels it. It soothes and composes the breast, seems to favour the vital motions, and to promote the healthful state of the human constitution; and it is rendered still more delightful by the consciousness of the gratitude and satisfaction which it must excite in him who is the object of it. Their mutual regard renders them happy in one another, and sympathy, with this mutual regard, makes them agreeable to every other person. With what pleasure do we look upon a family, through the whole of which reign mutual love and esteem, where the parents and children are companions for one another, without any other difference than what is made by respectful affection on the one side, and kind indulgence on the other; where freedom and fondness, mutual raillery and mutual kindness, show that no opposition of interest divides the brothers, nor any rivalship of favour sets the sisters at variance, and where everything presents us with the idea of peace, cheerfulness, harmony, and contentment? On the contrary, how uneasy are we made when we go into a house in which jarring contention sets one half of those who dwell in it against the other; where, amidst affected smoothness and complaisance, suspicious looks and sudden starts of passion betray the mutual jealousies which burn within them, and which are every moment ready to burst out through all the restraints which the presence of the company imposes?