The following pages owe their existence to Mr. Martin White, whose keen interest in comparative sociology led to the opening of special courses for its investigation in the University of London.

My thanks are due to Mr. P.J. Hartog, Academic Registrar of the University, as well as to Dr. and Mrs. E.R. Edwards, who inspired me with the courage to take the present task on my inexperienced shoulders. But above all I render the expression of my deepest obligation to Professor Walter Rippmann. Had it not been for his friendly interest and help, I would not have been able thus to come before an English public. For the peculiarities of thought and language, which, if nothing else, might at least make the booklet worthy of a perusal, I naturally assume the full responsibility myself.

With these prefatory words, I venture to submit this essay to the lenient reception of my readers.