In the words of author Greg Heisler, "Spirit-Led Preaching is a call issued to preachers, pastors, and teachers of homiletics to recover the Holy Spirit for expository preaching in the same way we have recovered the biblical text. . . . My plan for doing this is to recover the doctrine of pneumatology (the study of spiritual beings/phenomena) for our theology of preaching, resulting in a renewed emphasis on the powerful combination of Word and Spirit working together as the catalyst for powerful expository preaching." Heisler thoroughly examines how the Holy Spirit illuminates and empowers the preacher, opens the hearts of the hearers, and applies the message to their lives. Indeed, to ignore the Holy Spirit's role in sermon preparation and delivery would be a considerable oversight.