"Four centuries ago, Machiavelli was thinking of certain great problems of human society and writing two famous books. In so doing he reached scientific generalizations about the influence of the sentiments upon the actions of men and, through these actions, upon the fate of human societies. As a whole, these conclusions stand; but from this great and ingenious work of Machiavelli's almost no developments have followed. The science of statecraft and of the influence of the sentiments upon human behavior is little different to-day from what it was in in the 16th century."