Arthur Schopenhauer
Publisher: Dover Publications (2006)

What makes people hard-hearted is this, that each man has, or fancies he has, as much as he can bear in his own troubles. Hence if a man suddenly finds himself in an unusually happy position, it will in most cases result in his being sympathetic and kind. But if he has never been in any other than a happy position, or this becomes his permanent state, the effect of it is often just the contrary: it so far removes him from suffering that he is incapable of feeling any more sympathy with it. So it is that the poor often show themselves more ready to help than the rich.