The nineteenth century, observes Dr. Orr, was the century of Christian action and accomplishment. The social and political upheavals of the late eighteenth century were followed by a decline in Christian witness so serious that it seems as though Christianity was near death. In despair, Christian leaders prayed for Divine intervention; and answer came--a series of six great waves of evangelical renewal and advance which made the nineteenth century the Great Century of evangelism. From this study of Evangelical Revivals it is possible to trace a pattern of action and discover a progression of achievement which demonstrates that the same Spirit of God who moved the apostles continues to operate in the world. Dr. Orr suggests that the evangelical awakenings may be shown to be the foremost method of an Almighty God to promote the betterment of all mankind, and His primary instrument to win men to transforming faith in Himself.