It is evident a transition of the passions from the one object to the other is here in all reason to be expected; since the relation of ideas is supposed still to continue, and identity of impressions must produce a stronger connexion, than the most perfect resemblance, that can be imagined.

If a double relation, therefore, of impressions and ideas is able to produce a transition from one to the other, much more an identity of impressions with a relation of ideas.
Accordingly we find, that when we either love or hate any person, the passions seldom continue within their first bounds; but extend themselves towards all the contiguous objects, and comprehend the friends and relations of him we love or hate.

Nothing is more natural than to bear a kindness to one brother on account of our friendship for another, without any farther examination of his character.

A quarrel with one person gives us a hatred for the whole family, though entirely innocent of that, which displeases us.

Instances of this kind are every where to be met with.
There is only one difficulty in this experiment, which it will be necessary to account for, before we proceed any farther.