Such a conception is peculiarly agreeable, and makes us have an affectionate regard for every thing, that produces it, when the proper object of kindness and goodwill.
It is obvious, that people associate together according to their particular tempers and dispositions, and that men of gay tempers naturally love the gay; as the serious bear an affection to the serious.
This not only happens, where they remark this resemblance betwixt themselves and others, but also by the natural course of the disposition, and by a certain sympathy, which always arises betwixt similar characters.

Where they remark the resemblance, it operates after the manner of a relation, by producing a connexion of ideas.

Where they do not remark it, it operates by some other principle; and if this latter principle be similar to the former, it must be received as a confirmation of the foregoing reasoning.
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.