But this period of uncritical optimism was followed by a natural reaction. The pendulum stopped in its course, and soon began to swing in the opposite direction. Here, about 1880, the second stage may be said to have begun. Public opinion began to manifest a subtle change, and this mental attitude was accompanied by a physical manifestation in the form of a decreasing birth-rate. The rate of births began to fall rapidly, and has continued to fall steadily since that time. The writer above quoted from says of this second period: "In France the birth-rate fell slowly, in Italy more rapidly, and in England and Prussia still more rapidly. As, however, the fall began earliest in France, the birth-rate was lower there than in the other countries named. For the same reason it was lower in England than in Prussia, although England stands in this respect at almost exactly the same distance from Prussia today (1917) as thirty years ago, the fall having occurred at the same rate in both countries. It is quite possible that in the future it may become more rapid in Prussia than in England, for the birth-rate of Berlin is lower than the birth-rate of London, and urbanization is proceeding at a more rapid rate in Germany than in England." It is not difficult to arrive at the psychological reason underlying this great change in public opinion, as manifested in this second stage. In the first place, the wonderful era of world-expansion was arrested, by natural causes well understood by students of sociology. The ambitious dreams of world-empires were rudely interrupted. Moreover, public opinion was being affected by a quiet education along the lines of sociology and economics. The working classes began to perceive, on the one hand, the tendency of overpopulation to hold down, or even decrease, the scale of wages. The evils of over-production, and of under-consumption were dimly perceived. And, on the other hand, the capitalists began to perceive that another factor was at work--one which they had failed to include in their optimistic calculations. Instead of the cheaper wage rate which they had expected by reason of the over-abundance of human material, they found that the growth of popular education in the democratic countries had caused the working classes to demand greater comforts of life, and to oppose the cheapening of human labor. And at the same time, the masses began to revolt against the idea of raising children to become "cannon fodder" for ambitious autocratic rulers. The masses began to protest against selling their labor and their lives so cheaply.