And this leads to other observations upon communicated passions. I love my daughter less after she is married, and my mother less after a second marriage. The marriage of my son or my father diminishes not my affection so remarkably. The same observation holds with respect to friendship, gratitude, and other passions. The love I bear my friend, is but faintly extended to his married daughter. The resentment I have against a man, is readily extended against children who make part of his family: not so readily against children who are forisfamiliated, especially by marriage. This difference is also more remarkable in daughters than in sons. These are curious facts; and to evolve the cause we must examine minutely, that operation of the mind by which a passion is extended to a related object. In considering two things as related, the mind is not stationary, but passeth and repasseth from the one to the other, viewing the relation from each of them perhaps oftener than once. This holds more especially in considering a relation betwixt things of unequal rank, as betwixt the cause and the effect, or betwixt a principal and an accessory. In contemplating the relation betwixt a building and its ornaments, the mind is not satisfied with a single transition from the former to the latter. It must also view the relation, beginning at the latter, and passing from it to the former. This vibration of the mind in passing and repassing betwixt things that are related, explains the facts above mentioned. The mind passeth easily from the father to the daughter; but where the daughter is married, this new relation attracts the mind, and obstructs, in some measure, the return from the daughter to the father. Any obstruction the mind meets with in passing and repassing betwixt its objects, occasions a like obstruction in the communication of passion. The marriage of a male obstructs less the easiness of transition; because a male is less sunk by the relation of marriage than a female.