"First published, February, 1916 ... second edition, November, 1919, fifth impression, March, 1920.""The first two essays in this book were ... published in the Sociological review in 1908 and 1909"--Pref. Herd instinct and its bearing on the psychology of civilized man.--Sociological applications of the psychology of herd instinct.--Speculations upon the human mind in 1915.--Postscript of 1919.