T 2.2.4.6

'Tis 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 receiv'd as a confirmation of the foregoing reasoning.