These days religion is looked upon as a bug-bear. Yet mankind has not been able to give up religiosity. To banish religion is one thing; to try to free it from the bondage of pretenders quite another. We entirely agree with the view of the great modern scientist Max Planck that the religious element in his nature must be recognized and cultivated if all the powers of the human soul are to act together in perfect balance and harmony. True religiosity is the only bed-rock on which the great fabric of human progress can be built in safety. It is to expound this view that the books of the Religious Renaissance Series are being written.