Using George Leslie Mackay's autobiographic "From Far Formosa" as the core material, the author attempts a first-hand exploration of Mackay's theological thinking. Following the examination of the major factors informing Mackay's basic ideas and beliefs, i.e. the highland Free Church, the old Princeton school, and Prof. Alexander Duff, the author presents Mackay's thinking along the threefold framework of "faith in God," "love for humanity," and "passion for the land."