"We grudge no man a fortune which represents merely his own power and sagacity exercised with entire regard to the welfare of his fellows. But the fortune must not only be honorably obtained and well used; it is also essential that it should not represent a necessary incident of widespread, even though partial, economic privation. It is not even enough that the fortune should have been gained without doing damage to the community. We should only permit it to be gained and kept so long as the gaining and the keeping represent benefit to the community."