No attempt has been made in this volume to give a complete account of all aspects of the agricultural crisis, either in this, or in other countries. The theme throughout has been the prices of agricultural products, their cost of production, and the influences which have affected them during the last decade and caused them to rise or fall. In most writings upon agricultural economics, little attention has been paid to the economic causes which determine agricultural prices, and yet, in the last resort, this must remain the fundamental question of agricultural economics. The war and its consequences have provided an exceptional—in some respects unique—opportunity for the study of the underlying causes of price fluctuations, and to this branch of the subject the following pages are directed. I am indebted to Mr. H. D. Henderson and to Mr. R. J. Thompson, for very kindly reading the manuscript, and for several useful suggestions. I am also indebted to Mr. B. W. Phillips for his kindness in reading the proofs.