There is a sort of people in the world, to whom a man may be in the
wrong for doing services, upon a double score: first, because they never
deserved to have a good office done them; and, secondly, because, when
once engaged, it is so hard a matter to get well rid of their
acquaintance.
This fable is not an example of ingratitude, as at first sight it seems
to be, and as some of the mythologists have understood it; to make it a
parallel in that case, the Crane ought to have been under some
difficulties in his turn, and the Wolf have refused to assist him when
it was in his power. The whole stress of it lies in this: that we ought
to consider what kind of people they are to whom we are desired to do
good offices, before we do them; for he that grants a favour, or even
confides in a person of no honour, instead of finding his account in it,
comes off well if he is no sufferer.