Origen's homilies work with a consistent set of presuppositions about the nature and function of the Bible. Origen maintained that, with the exception of mechanical collisions, events are primarily caused by spiritual movements, and that these spiritual events are the primary content of Scripture. The physical events to which the Bible also refers are shaped by the same spiritual realities, but the spiritual causes generally make clearer sense than do the physical sequences of events. In any event, in Origen's methodology, the physical events are secondary; spiritual movements are the true "causes of things," and physical events are their "shadows." Human souls and the life of the church are shaped by the spiritual realities of which the Bible is an accurate "image" or pattern, and it is to the effect of spiritual realities upon human lives that the homilies direct attention. This exegetical pattern found in the Homilies is illuminated by passages in Origen's Treatise on Prayer and De Principiis, which discuss the relationships connecting shadow, image, and spiritual reality.