The springs of American civilization, unlike those of the elder world, lie revealed in the clear light of History. In appearance they are feeble; in reality, copious and full of force. Acting at the sources of life, instruments otherwise weak become mighty for good and evil, and men, lost elsewhere in the crowd, stand forth as agents of Destiny. In their toils, their sufferings, their conflicts, momentous questions were at stake, and issues vital to the future world, - the prevalence of races, the triumph of principles, health or disease, a blessing or a curse.