The philosophy of Karl Liebknecht as revealed in these pages leaves but a narrow ledge for heroes to stand on. To him the significant thing in history is, and has always been, the stirring of the masses of men at the bottom, their unconscious writhings, their awakenings, their conscious struggles and finally their gigantic, fearsome upthrust, which overturns all the little groups of clever men who have lived by holding these masses down. In these conflicts, kings, priests, leaders, heroes count for no more than flags or flying pennants. All great leaders, Cæsar, Mahomet, Luther, Napoleon, are instruments of popular movements, or at best manuscripts upon which the messages of their class and age have been written.