Jonathan Edwards is rightly titled America's first great theologian and philosopher, yet in terms of his historical influence he is foremost a preacher. This thesis links Edwards' philosophy to his preaching passion by demonstrating how his desire to establish a communication theory brought cohesion to his far-reaching philosophical interests. More specifically, this study shows how Edwards' speculative analysis on the composition of the human soul is motivated by his desire to configure a preaching strategy compatible with the soul's content and conduct. Jonathan Edwards' philosophy and its relation to his sermon writing is introduced in the first two chapters. The third chapter presents Edwards' conception of the human soul as an arrangement of mental powers which he calls "principles." Although the converted soul owns both natural and supernatural principles, Edwards' evangelistic preaching strategically targets the natural principles operating unaccompanied in the sinner. Focusing on Edwards' preaching to the unconverted, the next four chapters are devoted to an examination of the four natural principles: human reason; simple imagination; common affection and natural conscience. Each natural principle is placed within Edwards' communication theory while sermon extracts are called in to demonstrate the principle's function in Edwards' awakening preaching. The significance of this study is enhanced by the introduction of 100 unpublished sermons which are cited and used as background reference. These unpublished sermon portions offer a rare glimpse into Edwards' homiletic genius and in many cases appear in this study for the first time in print.