This book has been professionally retyped and reformatted to fit modern day standards by officials of the Portuguese Institute of Higher Studies in Geopolitics and Auxiliary Sciences. * Organised crowds have always played an important part in the life of peoples, but this part has never been of such moment as at present. The substitution of the unconscious action of crowds for the conscious activity of individuals is one of the principal characteristics of the present age. I have endeavoured to examine the difficult problem presented by crowds in a purely scientific manner-that is, by making...