“[A] permanent possibility of selfishness arises from the mere fact of having a self, and not from any accidents of education or ill-treatment. And the weakness of all Utopias is this, that they take the greatest difficulty of man and assume it to be overcome, and then give an elaborate account of the overcoming of the smaller ones. They first assume that no man will want more than his share, and then are very ingenious in explaining whether his share will be delivered by motor-car or balloon.”