The man who attempts to point out the trends in any particular human activity must to a certain extent assume the rôle of a prophet—and that is a delicate thing to do; for events are bound to take place relentlessly and with little regard for the words of the prophet. If he has been lucky in his forecasts he usually receives but little credit, but if he has been wrong he is not allowed to forget.
There are two methods which the prophet may use. The first, and the more reliable, is to foretell the future by extending the knowledge of the past. In this method, however, there are two possible weaknesses. Our prophet may have only a dim or distorted view of ancient knowledge and facts on which to base his forecasts; again, recent events which are to prove of great importance may be so close to him that