It's no secret that one of the hardest things about writing and preaching and teaching is the work of narrowing - bringing one thing into focus. Read one Faulkner sentence or listen to one of Bernard's homilies and witness this work at its best.
Plowing through this week's passage or creating a new world via a short story, the author makes decisions about what stays and what goes. The sharpening process tends to be painful, for it usually means rejecting various good ideas/themes in order to focus on one matter. Hence, a shovel is no good for digging a post-hole. To achieve proper depth without disturbing a large area of soil/rock around the post, post-hole diggers fit the bill (or tractor borne augers if you're lucky).
I hope to preach the gospel clearly and well, which requires sound and thorough learning - a willingness to contently dig in one place for a while. I have to remember that there's always next week or next time, so it's ok and even necessary to reject a handful of good things as I prepare. After all, when it comes to writing and teaching through scripture, in the words of Robert Earl Keen, "the road goes on forever and the party never ends."