"Ideas, good and bad, are productive, and a teacher of ideas can have a vast influence in the propagating of good and bad ideas. We have only to review the influence of German Idealism upon German and English Romanticism to see this realized. Similarly, today, in the United States, we are reaping the fruit, good and bad, of ideas that have been sown during the past several decades. Some of them we accept, some we reject. All of them deserve our investigation, insofar as it is within our power to investigate them in order that, as followers of truth, we may sift the good from the bad."--From the preface.
