The only thing that one really knows about human nature is that it changes. Change is the one quality we can predicate of it.
We think that we are generous because we credit our neighbor with those virtues that are likely to benefit ourselves. We praise the banker that we may overdraw our account, and find good qualities in the highwayman in the hope that he may spare our pockets.
After a good quality dinner one will be able to forgive anybody, still one's own relations.