The views expressed in this article are purely personal. They are not to be attributed to any institution with which the writer is connected. They do not reflect any opinions of the Board of Governors of the Federal Reserve System or of the Federal Reserve Bank of Chicago. The writer is indebted to Messrs, L. W. Mints and John K. Langum for numerous suggestions and criticisms of this manuscript. They, too, are not responsible for the author's ideas, errors or judgments.