The material incorporated in this study was originally meant to be presented to Columbia University in fulfilment of the last requirement for the degree of Doctor of Philosophy. As the work progressed, however, and by the time the first painful fifty pages had been put on paper and tom up again, I became more and more aware that I had emerged out of the initial period of reading and study with convictions and aspirations which it would be difficult tot clothe in the sober garments of modesty and reserve rightly prescribed for a University thesis. Soon after the last words of the manuscript were written (March 1934) it furthermore became clear that owing to the pressure of other work, presentation in thesis form would mean indefinite delay, delay which would almost certainly render a complete revision inevitable. These considerations have led me to the decision to send out my brazen unkempt first-born under his own flag, to meet what- ever fate he deserves. In so doing I have one great regret. Time, that relentless foe of the writer on current events, has not allowed me to weave into the text all of the wise and helpful suggestions which my academical sponsor, Professor H. Parker Willis, with his generous understanding of a young writer's problems and ambitions, has so kindly offered. Had I been able to do so, this little book would have presented a far more polished aspect.